---
title: streamText
description: API Reference for streamText.
---

# `streamText()`

Streams text generations from a language model.

You can use the streamText function for interactive use cases such as chat bots and other real-time applications. You can also generate UI components with tools.

```ts
import { streamText } from 'ai';
__PROVIDER_IMPORT__;

const { textStream } = streamText({
  model: __MODEL__,
  prompt: 'Invent a new holiday and describe its traditions.',
});

for await (const textPart of textStream) {
  process.stdout.write(textPart);
}
```

To see `streamText` in action, check out [these examples](#examples).

## Import

<Snippet text={`import { streamText } from "ai"`} prompt={false} />

## API Signature

### Parameters

<PropertiesTable
  content={[
    {
      name: 'model',
      type: 'LanguageModel',
      description: "The language model to use. Example: openai('gpt-4.1')",
    },
    {
      name: 'system',
      type: 'string | SystemModelMessage | SystemModelMessage[]',
      description:
        'The system prompt to use that specifies the behavior of the model.',
    },
    {
      name: 'prompt',
      type: 'string | Array<SystemModelMessage | UserModelMessage | AssistantModelMessage | ToolModelMessage>',
      description: 'The input prompt to generate the text from.',
    },
    {
      name: 'messages',
      type: 'Array<SystemModelMessage | UserModelMessage | AssistantModelMessage | ToolModelMessage>',
      description:
        'A list of messages that represent a conversation. Automatically converts UI messages from the useChat hook.',
      properties: [
        {
          type: 'SystemModelMessage',
          parameters: [
            {
              name: 'role',
              type: "'system'",
              description: 'The role for the system message.',
            },
            {
              name: 'content',
              type: 'string',
              description: 'The content of the message.',
            },
          ],
        },
        {
          type: 'UserModelMessage',
          parameters: [
            {
              name: 'role',
              type: "'user'",
              description: 'The role for the user message.',
            },
            {
              name: 'content',
              type: 'string | Array<TextPart | ImagePart | FilePart>',
              description: 'The content of the message.',
              properties: [
                {
                  type: 'TextPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'text'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The text content of the message part.',
                    },
                  ],
                },
                {
                  type: 'ImagePart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'image'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'image',
                      type: 'string | Uint8Array | Buffer | ArrayBuffer | URL',
                      description:
                        'The image content of the message part. String are either base64 encoded content, base64 data URLs, or http(s) URLs.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      isOptional: true,
                      description: 'The IANA media type of the image.',
                    },
                  ],
                },
                {
                  type: 'FilePart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'file'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'data',
                      type: 'string | Uint8Array | Buffer | ArrayBuffer | URL',
                      description:
                        'The file content of the message part. String are either base64 encoded content, base64 data URLs, or http(s) URLs.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                  ],
                },
              ],
            },
          ],
        },
        {
          type: 'AssistantModelMessage',
          parameters: [
            {
              name: 'role',
              type: "'assistant'",
              description: 'The role for the assistant message.',
            },
            {
              name: 'content',
              type: 'string | Array<TextPart | FilePart | ReasoningPart | ToolCallPart>',
              description: 'The content of the message.',
              properties: [
                {
                  type: 'TextPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'text'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The text content of the message part.',
                    },
                  ],
                },
                {
                  type: 'ReasoningPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'reasoning'",
                      description: 'The type of the reasoning part.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The reasoning text.',
                    },
                  ],
                },
                {
                  type: 'FilePart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'file'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'data',
                      type: 'string | Uint8Array | Buffer | ArrayBuffer | URL',
                      description:
                        'The file content of the message part. String are either base64 encoded content, base64 data URLs, or http(s) URLs.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                    {
                      name: 'filename',
                      type: 'string',
                      description: 'The name of the file.',
                      isOptional: true,
                    },
                  ],
                },
                {
                  type: 'ToolCallPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-call'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description: 'The id of the tool call.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool, which typically would be the name of the function.',
                    },
                    {
                      name: 'input',
                      type: 'object based on zod schema',
                      description:
                        'Parameters generated by the model to be used by the tool.',
                    },
                  ],
                },
              ],
            },
          ],
        },
        {
          type: 'ToolModelMessage',
          parameters: [
            {
              name: 'role',
              type: "'tool'",
              description: 'The role for the assistant message.',
            },
            {
              name: 'content',
              type: 'Array<ToolResultPart>',
              description: 'The content of the message.',
              properties: [
                {
                  type: 'ToolResultPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-result'",
                      description: 'The type of the message part.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description:
                        'The id of the tool call the result corresponds to.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool the result corresponds to.',
                    },
                    {
                      name: 'result',
                      type: 'unknown',
                      description:
                        'The result returned by the tool after execution.',
                    },
                    {
                      name: 'isError',
                      type: 'boolean',
                      isOptional: true,
                      description:
                        'Whether the result is an error or an error message.',
                    },
                  ],
                },
              ],
            },
          ],
        },
      ],
    },
    {
      name: 'tools',
      type: 'ToolSet',
      description:
        'Tools that are accessible to and can be called by the model. The model needs to support calling tools.',
      properties: [
        {
          type: 'Tool',
          parameters: [
            {
              name: 'description',
              isOptional: true,
              type: 'string',
              description:
                'Information about the purpose of the tool including details on how and when it can be used by the model.',
            },
            {
              name: 'inputSchema',
              type: 'Zod Schema | JSON Schema',
              description:
                'The schema of the input that the tool expects. The language model will use this to generate the input. It is also used to validate the output of the language model. Use descriptions to make the input understandable for the language model. You can either pass in a Zod schema or a JSON schema (using the `jsonSchema` function).',
            },
            {
              name: 'execute',
              isOptional: true,
              type: 'async (parameters: T, options: ToolExecutionOptions) => RESULT',
              description:
                'An async function that is called with the arguments from the tool call and produces a result. If not provided, the tool will not be executed automatically.',
              properties: [
                {
                  type: 'ToolExecutionOptions',
                  parameters: [
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description:
                        'The ID of the tool call. You can use it e.g. when sending tool-call related information with stream data.',
                    },
                    {
                      name: 'messages',
                      type: 'ModelMessage[]',
                      description:
                        'Messages that were sent to the language model to initiate the response that contained the tool call. The messages do not include the system prompt nor the assistant response that contained the tool call.',
                    },
                    {
                      name: 'abortSignal',
                      type: 'AbortSignal',
                      description:
                        'An optional abort signal that indicates that the overall operation should be aborted.',
                    },
                  ],
                },
              ],
            },
          ],
        },
      ],
    },
    {
      name: 'toolChoice',
      isOptional: true,
      type: '"auto" | "none" | "required" | { "type": "tool", "toolName": string }',
      description:
        'The tool choice setting. It specifies how tools are selected for execution. The default is "auto". "none" disables tool execution. "required" requires tools to be executed. { "type": "tool", "toolName": string } specifies a specific tool to execute.',
    },
    {
      name: 'maxOutputTokens',
      type: 'number',
      isOptional: true,
      description: 'Maximum number of tokens to generate.',
    },
    {
      name: 'temperature',
      type: 'number',
      isOptional: true,
      description:
        'Temperature setting. The value is passed through to the provider. The range depends on the provider and model. It is recommended to set either `temperature` or `topP`, but not both.',
    },
    {
      name: 'topP',
      type: 'number',
      isOptional: true,
      description:
        'Nucleus sampling. The value is passed through to the provider. The range depends on the provider and model. It is recommended to set either `temperature` or `topP`, but not both.',
    },
    {
      name: 'topK',
      type: 'number',
      isOptional: true,
      description:
        'Only sample from the top K options for each subsequent token. Used to remove "long tail" low probability responses. Recommended for advanced use cases only. You usually only need to use temperature.',
    },
    {
      name: 'presencePenalty',
      type: 'number',
      isOptional: true,
      description:
        'Presence penalty setting. It affects the likelihood of the model to repeat information that is already in the prompt. The value is passed through to the provider. The range depends on the provider and model.',
    },
    {
      name: 'frequencyPenalty',
      type: 'number',
      isOptional: true,
      description:
        'Frequency penalty setting. It affects the likelihood of the model to repeatedly use the same words or phrases. The value is passed through to the provider. The range depends on the provider and model.',
    },
    {
      name: 'stopSequences',
      type: 'string[]',
      isOptional: true,
      description:
        'Sequences that will stop the generation of the text. If the model generates any of these sequences, it will stop generating further text.',
    },
    {
      name: 'seed',
      type: 'number',
      isOptional: true,
      description:
        'The seed (integer) to use for random sampling. If set and supported by the model, calls will generate deterministic results.',
    },
    {
      name: 'maxRetries',
      type: 'number',
      isOptional: true,
      description:
        'Maximum number of retries. Set to 0 to disable retries. Default: 2.',
    },
    {
      name: 'abortSignal',
      type: 'AbortSignal',
      isOptional: true,
      description:
        'An optional abort signal that can be used to cancel the call.',
    },
    {
      name: 'timeout',
      type: 'number | { totalMs?: number; stepMs?: number; chunkMs?: number }',
      isOptional: true,
      description:
        'Timeout in milliseconds. Can be specified as a number or as an object with totalMs, stepMs, and/or chunkMs properties. totalMs sets the total timeout for the entire call. stepMs sets the timeout for each individual step (LLM call), useful for multi-step generations. chunkMs sets the timeout between stream chunks - the call will abort if no new chunk is received within this duration, useful for detecting stalled streams. Can be used alongside abortSignal.',
    },
    {
      name: 'headers',
      type: 'Record<string, string | undefined>',
      isOptional: true,
      description:
        'Additional HTTP headers to be sent with the request. Only applicable for HTTP-based providers.',
    },
    {
      name: 'experimental_telemetry',
      type: 'TelemetrySettings',
      isOptional: true,
      description: 'Telemetry configuration. Experimental feature.',
      properties: [
        {
          type: 'TelemetrySettings',
          parameters: [
            {
              name: 'isEnabled',
              type: 'boolean',
              isOptional: true,
              description:
                'Enable or disable telemetry. Disabled by default while experimental.',
            },
            {
              name: 'recordInputs',
              type: 'boolean',
              isOptional: true,
              description:
                'Enable or disable input recording. Enabled by default.',
            },
            {
              name: 'recordOutputs',
              type: 'boolean',
              isOptional: true,
              description:
                'Enable or disable output recording. Enabled by default.',
            },
            {
              name: 'functionId',
              type: 'string',
              isOptional: true,
              description:
                'Identifier for this function. Used to group telemetry data by function.',
            },
            {
              name: 'metadata',
              isOptional: true,
              type: 'Record<string, string | number | boolean | Array<null | undefined | string> | Array<null | undefined | number> | Array<null | undefined | boolean>>',
              description:
                'Additional information to include in the telemetry data.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_transform',
      type: 'StreamTextTransform | Array<StreamTextTransform>',
      isOptional: true,
      description:
        'Optional stream transformations. They are applied in the order they are provided. The stream transformations must maintain the stream structure for streamText to work correctly.',
      properties: [
        {
          type: 'StreamTextTransform',
          parameters: [
            {
              name: 'transform',
              type: '(options: TransformOptions) => TransformStream<TextStreamPart<TOOLS>, TextStreamPart<TOOLS>>',
              description: 'A transformation that is applied to the stream.',
              properties: [
                {
                  type: 'TransformOptions',
                  parameters: [
                    {
                      name: 'stopStream',
                      type: '() => void',
                      description: 'A function that stops the stream.',
                    },
                    {
                      name: 'tools',
                      type: 'TOOLS',
                      description: 'The tools that are available.',
                    },
                  ],
                },
              ],
            },
          ],
        },
      ],
    },
    {
      name: 'includeRawChunks',
      type: 'boolean',
      isOptional: true,
      description:
        'Whether to include raw chunks from the provider in the stream. When enabled, you will receive raw chunks with type "raw" that contain the unprocessed data from the provider. This allows access to cutting-edge provider features not yet wrapped by the AI SDK. Defaults to false.',
    },
    {
      name: 'providerOptions',
      type: 'Record<string,JSONObject> | undefined',
      isOptional: true,
      description:
        'Provider-specific options. The outer key is the provider name. The inner values are the metadata. Details depend on the provider.',
    },
    {
      name: 'activeTools',
      type: 'Array<TOOLNAME> | undefined',
      isOptional: true,
      description:
        'The tools that are currently active. All tools are active by default.',
    },
    {
      name: 'stopWhen',
      type: 'StopCondition<TOOLS> | Array<StopCondition<TOOLS>>',
      isOptional: true,
      description:
        'Condition for stopping the generation when there are tool results in the last step. When the condition is an array, any of the conditions can be met to stop the generation. Default: stepCountIs(1).',
    },
    {
      name: 'prepareStep',
      type: '(options: PrepareStepOptions) => PrepareStepResult<TOOLS> | Promise<PrepareStepResult<TOOLS>>',
      isOptional: true,
      description:
        'Optional function that you can use to provide different settings for a step. You can modify the model, tool choices, active tools, system prompt, and input messages for each step.',
      properties: [
        {
          type: 'PrepareStepFunction<TOOLS>',
          parameters: [
            {
              name: 'options',
              type: 'object',
              description: 'The options for the step.',
              properties: [
                {
                  type: 'PrepareStepOptions',
                  parameters: [
                    {
                      name: 'steps',
                      type: 'Array<StepResult<TOOLS>>',
                      description: 'The steps that have been executed so far.',
                    },
                    {
                      name: 'stepNumber',
                      type: 'number',
                      description:
                        'The number of the step that is being executed.',
                    },
                    {
                      name: 'model',
                      type: 'LanguageModel',
                      description: 'The model that is being used.',
                    },
                    {
                      name: 'messages',
                      type: 'Array<ModelMessage>',
                      description:
                        'The messages that will be sent to the model for the current step.',
                    },
                    {
                      name: 'experimental_context',
                      type: 'unknown',
                      isOptional: true,
                      description:
                        'The context passed via the experimental_context setting (experimental).',
                    },
                  ],
                },
              ],
            },
          ],
        },
        {
          type: 'PrepareStepResult<TOOLS>',
          description:
            'Return value that can modify settings for the current step.',
          parameters: [
            {
              name: 'model',
              type: 'LanguageModel',
              isOptional: true,
              description:
                'Optionally override which LanguageModel instance is used for this step.',
            },
            {
              name: 'toolChoice',
              type: 'ToolChoice<TOOLS>',
              isOptional: true,
              description:
                'Optionally set which tool the model must call, or provide tool call configuration for this step.',
            },
            {
              name: 'activeTools',
              type: 'Array<keyof TOOLS>',
              isOptional: true,
              description:
                'If provided, only these tools are enabled/available for this step.',
            },
            {
              name: 'system',
              type: 'string | SystemModelMessage | SystemModelMessage[]',
              isOptional: true,
              description:
                'Optionally override the system message(s) sent to the model for this step.',
            },
            {
              name: 'messages',
              type: 'Array<ModelMessage>',
              isOptional: true,
              description:
                'Optionally override the full set of messages sent to the model for this step.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              isOptional: true,
              description:
                'Context that is passed into tool execution. Experimental. Changing the context will affect the context in this step and all subsequent steps.',
            },
            {
              name: 'providerOptions',
              type: 'ProviderOptions',
              isOptional: true,
              description:
                'Additional provider-specific options for this step. Can be used to pass provider-specific configuration such as container IDs for Anthropic code execution.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_context',
      type: 'unknown',
      isOptional: true,
      description:
        'Context that is passed into tool execution. Experimental (can break in patch releases).',
    },
    {
      name: 'experimental_download',
      type: '(requestedDownloads: Array<{ url: URL; isUrlSupportedByModel: boolean }>) => Promise<Array<null | { data: Uint8Array; mediaType?: string }>>',
      isOptional: true,
      description:
        'Custom download function to control how URLs are fetched when they appear in prompts. By default, files are downloaded if the model does not support the URL for the given media type. Experimental feature. Return null to pass the URL directly to the model (when supported), or return downloaded content with data and media type.',
    },
    {
      name: 'experimental_include',
      type: '{ requestBody?: boolean }',
      isOptional: true,
      description:
        'Controls inclusion of request body in step results. By default, the body is included. When processing many large payloads (e.g., images), set requestBody to false to reduce memory usage. Experimental feature.',
      properties: [
        {
          type: 'Object',
          parameters: [
            {
              name: 'requestBody',
              type: 'boolean',
              isOptional: true,
              description:
                'Whether to include the request body in step results. The request body can be large when sending images or files. Default: true.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_repairToolCall',
      type: '(options: ToolCallRepairOptions) => Promise<LanguageModelV3ToolCall | null>',
      isOptional: true,
      description:
        'A function that attempts to repair a tool call that failed to parse. Return either a repaired tool call or null if the tool call cannot be repaired.',
      properties: [
        {
          type: 'ToolCallRepairOptions',
          parameters: [
            {
              name: 'system',
              type: 'string | SystemModelMessage | SystemModelMessage[] | undefined',
              description: 'The system prompt.',
            },
            {
              name: 'messages',
              type: 'ModelMessage[]',
              description: 'The messages in the current generation step.',
            },
            {
              name: 'toolCall',
              type: 'LanguageModelV3ToolCall',
              description: 'The tool call that failed to parse.',
            },
            {
              name: 'tools',
              type: 'TOOLS',
              description: 'The tools that are available.',
            },
            {
              name: 'parameterSchema',
              type: '(options: { toolName: string }) => JSONSchema7',
              description:
                'A function that returns the JSON Schema for a tool.',
            },
            {
              name: 'error',
              type: 'NoSuchToolError | InvalidToolInputError',
              description:
                'The error that occurred while parsing the tool call.',
            },
          ],
        },
      ],
    },
    {
      name: 'onChunk',
      type: '(event: OnChunkResult) => Promise<void> |void',
      isOptional: true,
      description:
        'Callback that is called for each chunk of the stream. The stream processing will pause until the callback promise is resolved.',
      properties: [
        {
          type: 'OnChunkResult',
          parameters: [
            {
              name: 'chunk',
              type: 'TextStreamPart',
              description: 'The chunk of the stream.',
              properties: [
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'text'",
                      description:
                        'The type to identify the object as text delta.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The text delta.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'reasoning'",
                      description:
                        'The type to identify the object as reasoning.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The reasoning text delta.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'source'",
                      description: 'The type to identify the object as source.',
                    },
                    {
                      name: 'source',
                      type: 'Source',
                      description: 'The source.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-call'",
                      description:
                        'The type to identify the object as tool call.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description: 'The id of the tool call.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool, which typically would be the name of the function.',
                    },
                    {
                      name: 'input',
                      type: 'object based on zod schema',
                      description:
                        'Parameters generated by the model to be used by the tool.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-call-streaming-start'",
                      description:
                        'Indicates the start of a tool call streaming. Only available when streaming tool calls.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description: 'The id of the tool call.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool, which typically would be the name of the function.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-call-delta'",
                      description:
                        'The type to identify the object as tool call delta. Only available when streaming tool calls.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description: 'The id of the tool call.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool, which typically would be the name of the function.',
                    },
                    {
                      name: 'argsTextDelta',
                      type: 'string',
                      description: 'The text delta of the tool call arguments.',
                    },
                  ],
                },
                {
                  type: 'TextStreamPart',
                  description: 'The result of a tool call execution.',
                  parameters: [
                    {
                      name: 'type',
                      type: "'tool-result'",
                      description:
                        'The type to identify the object as tool result.',
                    },
                    {
                      name: 'toolCallId',
                      type: 'string',
                      description: 'The id of the tool call.',
                    },
                    {
                      name: 'toolName',
                      type: 'string',
                      description:
                        'The name of the tool, which typically would be the name of the function.',
                    },
                    {
                      name: 'input',
                      type: 'object based on zod schema',
                      description:
                        'Parameters generated by the model to be used by the tool.',
                    },
                    {
                      name: 'output',
                      type: 'any',
                      description:
                        'The result returned by the tool after execution has completed.',
                    },
                  ],
                },
              ],
            },
          ],
        },
      ],
    },
    {
      name: 'onError',
      type: '(event: OnErrorResult) => Promise<void> |void',
      isOptional: true,
      description:
        'Callback that is called when an error occurs during streaming. You can use it to log errors.',
      properties: [
        {
          type: 'OnErrorResult',
          parameters: [
            {
              name: 'error',
              type: 'unknown',
              description: 'The error that occurred.',
            },
          ],
        },
      ],
    },
    {
      name: 'output',
      type: 'Output',
      isOptional: true,
      description:
        'Specification for parsing structured outputs from the LLM response.',
      properties: [
        {
          type: 'Output',
          parameters: [
            {
              name: 'Output.text()',
              type: 'Output',
              description:
                'Output specification for text generation (default).',
            },
            {
              name: 'Output.object()',
              type: 'Output',
              description:
                'Output specification for typed object generation using schemas. When the model generates a text response, it will return an object that matches the schema.',
              properties: [
                {
                  type: 'Options',
                  parameters: [
                    {
                      name: 'schema',
                      type: 'Schema<OBJECT>',
                      description: 'The schema of the object to generate.',
                    },
                    {
                      name: 'name',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional name of the output. Used by some providers for additional LLM guidance.',
                    },
                    {
                      name: 'description',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional description of the output. Used by some providers for additional LLM guidance.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'Output.array()',
              type: 'Output',
              description:
                'Output specification for array generation. When the model generates a text response, it will return an array of elements.',
              properties: [
                {
                  type: 'Options',
                  parameters: [
                    {
                      name: 'element',
                      type: 'Schema<ELEMENT>',
                      description:
                        'The schema of the array elements to generate.',
                    },
                    {
                      name: 'name',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional name of the output. Used by some providers for additional LLM guidance.',
                    },
                    {
                      name: 'description',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional description of the output. Used by some providers for additional LLM guidance.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'Output.choice()',
              type: 'Output',
              description:
                'Output specification for choice generation. When the model generates a text response, it will return a one of the choice options.',
              properties: [
                {
                  type: 'Options',
                  parameters: [
                    {
                      name: 'options',
                      type: 'Array<string>',
                      description: 'The available choices.',
                    },
                    {
                      name: 'name',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional name of the output. Used by some providers for additional LLM guidance.',
                    },
                    {
                      name: 'description',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional description of the output. Used by some providers for additional LLM guidance.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'Output.json()',
              type: 'Output',
              description:
                'Output specification for unstructured JSON generation. When the model generates a text response, it will return a JSON object.',
              properties: [
                {
                  type: 'Options',
                  parameters: [
                    {
                      name: 'name',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional name of the output. Used by some providers for additional LLM guidance.',
                    },
                    {
                      name: 'description',
                      type: 'string',
                      isOptional: true,
                      description:
                        'Optional description of the output. Used by some providers for additional LLM guidance.',
                    },
                  ],
                },
              ],
            },
          ],
        },
      ],
    },
    {
      name: 'onStepFinish',
      type: '(result: onStepFinishResult) => Promise<void> | void',
      isOptional: true,
      description: 'Callback that is called when a step is finished.',
      properties: [
        {
          type: 'onStepFinishResult',
          parameters: [
            {
              name: 'stepType',
              type: '"initial" | "continue" | "tool-result"',
              description:
                'The type of step. The first step is always an "initial" step, and subsequent steps are either "continue" steps or "tool-result" steps.',
            },
            {
              name: 'finishReason',
              type: '"stop" | "length" | "content-filter" | "tool-calls" | "error" | "other"',
              description:
                'The unified finish reason why the generation finished.',
            },
            {
              name: 'rawFinishReason',
              type: 'string | undefined',
              description:
                'The raw reason why the generation finished (from the provider).',
            },
            {
              name: 'usage',
              type: 'LanguageModelUsage',
              description: 'The token usage of the step.',
              properties: [
                {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description:
                        'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description:
                        'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description:
                                'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description:
                        "Raw usage information from the provider. This is the provider's original usage information and may include additional fields.",
                    },
                  ],
                },
              ],
            },
            {
              name: 'text',
              type: 'string',
              description: 'The full text that has been generated.',
            },
            {
              name: 'reasoningText',
              type: 'string | undefined',
              description:
                'The reasoning text of the model (only available for some models).',
            },
            {
              name: 'sources',
              type: 'Array<Source>',
              description:
                'Sources that have been used as input to generate the response. For multi-step generation, the sources are accumulated from all steps.',
              properties: [
                {
                  type: 'Source',
                  parameters: [
                    {
                      name: 'sourceType',
                      type: "'url'",
                      description:
                        'A URL source. This is return by web search RAG models.',
                    },
                    {
                      name: 'id',
                      type: 'string',
                      description: 'The ID of the source.',
                    },
                    {
                      name: 'url',
                      type: 'string',
                      description: 'The URL of the source.',
                    },
                    {
                      name: 'title',
                      type: 'string',
                      isOptional: true,
                      description: 'The title of the source.',
                    },
                    {
                      name: 'providerMetadata',
                      type: 'SharedV2ProviderMetadata',
                      isOptional: true,
                      description:
                        'Additional provider metadata for the source.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'files',
              type: 'Array<GeneratedFile>',
              description: 'All files that were generated in this step.',
              properties: [
                {
                  type: 'GeneratedFile',
                  parameters: [
                    {
                      name: 'base64',
                      type: 'string',
                      description: 'File as a base64 encoded string.',
                    },
                    {
                      name: 'uint8Array',
                      type: 'Uint8Array',
                      description: 'File as a Uint8Array.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'toolCalls',
              type: 'ToolCall[]',
              description: 'The tool calls that have been executed.',
            },
            {
              name: 'toolResults',
              type: 'ToolResult[]',
              description: 'The tool results that have been generated.',
            },
            {
              name: 'warnings',
              type: 'Warning[] | undefined',
              description:
                'Warnings from the model provider (e.g. unsupported settings).',
            },
            {
              name: 'response',
              type: 'Response',
              isOptional: true,
              description: 'Response metadata.',
              properties: [
                {
                  type: 'Response',
                  parameters: [
                    {
                      name: 'id',
                      type: 'string',
                      description:
                        'The response identifier. The AI SDK uses the ID from the provider response when available, and generates an ID otherwise.',
                    },
                    {
                      name: 'modelId',
                      type: 'string',
                      description:
                        'The model that was used to generate the response. The AI SDK uses the response model from the provider response when available, and the model from the function call otherwise.',
                    },
                    {
                      name: 'timestamp',
                      type: 'Date',
                      description:
                        'The timestamp of the response. The AI SDK uses the response timestamp from the provider response when available, and creates a timestamp otherwise.',
                    },
                    {
                      name: 'headers',
                      isOptional: true,
                      type: 'Record<string, string>',
                      description: 'Optional response headers.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'isContinued',
              type: 'boolean',
              description:
                'True when there will be a continuation step with a continuation text.',
            },
            {
              name: 'providerMetadata',
              type: 'Record<string,JSONObject> | undefined',
              isOptional: true,
              description:
                'Optional metadata from the provider. The outer key is the provider name. The inner values are the metadata. Details depend on the provider.',
            },
          ],
        },
      ],
    },
    {
      name: 'onFinish',
      type: '(result: OnFinishResult) => Promise<void> | void',
      isOptional: true,
      description:
        'Callback that is called when the LLM response and all request tool executions (for tools that have an `execute` function) are finished.',
      properties: [
        {
          type: 'OnFinishResult',
          parameters: [
            {
              name: 'finishReason',
              type: '"stop" | "length" | "content-filter" | "tool-calls" | "error" | "other"',
              description:
                'The unified finish reason why the generation finished.',
            },
            {
              name: 'rawFinishReason',
              type: 'string | undefined',
              description:
                'The raw reason why the generation finished (from the provider).',
            },
            {
              name: 'usage',
              type: 'LanguageModelUsage',
              description: 'The token usage of last step.',
              properties: [
                {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description:
                        'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description:
                        'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description:
                                'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description:
                        "Raw usage information from the provider. This is the provider's original usage information and may include additional fields.",
                    },
                  ],
                },
              ],
            },
            {
              name: 'totalUsage',
              type: 'LanguageModelUsage',
              description: 'The total token usage from all steps.',
              properties: [
                {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description: 'The number of input (prompt) tokens used.',
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description:
                        'The number of output (completion) tokens used.',
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description:
                        'The total number of tokens as reported by the provider. This number might be different from the sum of inputTokens and outputTokens and e.g. include reasoning tokens or other overhead.',
                    },
                    {
                      name: 'reasoningTokens',
                      type: 'number | undefined',
                      isOptional: true,
                      description: 'The number of reasoning tokens used.',
                    },
                    {
                      name: 'cachedInputTokens',
                      type: 'number | undefined',
                      isOptional: true,
                      description: 'The number of cached input tokens.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'providerMetadata',
              type: 'Record<string,JSONObject> | undefined',
              description:
                'Optional metadata from the provider. The outer key is the provider name. The inner values are the metadata. Details depend on the provider.',
            },
            {
              name: 'text',
              type: 'string',
              description: 'The full text that has been generated.',
            },
            {
              name: 'reasoning',
              type: 'string | undefined',
              description:
                'The reasoning text of the model (only available for some models).',
            },
            {
              name: 'reasoning',
              type: 'Array<ReasoningDetail>',
              description:
                'The reasoning details of the model (only available for some models).',
              properties: [
                {
                  type: 'ReasoningDetail',
                  parameters: [
                    {
                      name: 'type',
                      type: "'text'",
                      description: 'The type of the reasoning detail.',
                    },
                    {
                      name: 'text',
                      type: 'string',
                      description: 'The text content (only for type "text").',
                    },
                    {
                      name: 'signature',
                      type: 'string',
                      isOptional: true,
                      description: 'Optional signature (only for type "text").',
                    },
                  ],
                },
                {
                  type: 'ReasoningDetail',
                  parameters: [
                    {
                      name: 'type',
                      type: "'redacted'",
                      description: 'The type of the reasoning detail.',
                    },
                    {
                      name: 'data',
                      type: 'string',
                      description:
                        'The redacted data content (only for type "redacted").',
                    },
                  ],
                },
              ],
            },
            {
              name: 'sources',
              type: 'Array<Source>',
              description:
                'Sources that have been used as input to generate the response. For multi-step generation, the sources are accumulated from all steps.',
              properties: [
                {
                  type: 'Source',
                  parameters: [
                    {
                      name: 'sourceType',
                      type: "'url'",
                      description:
                        'A URL source. This is return by web search RAG models.',
                    },
                    {
                      name: 'id',
                      type: 'string',
                      description: 'The ID of the source.',
                    },
                    {
                      name: 'url',
                      type: 'string',
                      description: 'The URL of the source.',
                    },
                    {
                      name: 'title',
                      type: 'string',
                      isOptional: true,
                      description: 'The title of the source.',
                    },
                    {
                      name: 'providerMetadata',
                      type: 'SharedV2ProviderMetadata',
                      isOptional: true,
                      description:
                        'Additional provider metadata for the source.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'files',
              type: 'Array<GeneratedFile>',
              description: 'Files that were generated in the final step.',
              properties: [
                {
                  type: 'GeneratedFile',
                  parameters: [
                    {
                      name: 'base64',
                      type: 'string',
                      description: 'File as a base64 encoded string.',
                    },
                    {
                      name: 'uint8Array',
                      type: 'Uint8Array',
                      description: 'File as a Uint8Array.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'toolCalls',
              type: 'ToolCall[]',
              description: 'The tool calls that have been executed.',
            },
            {
              name: 'toolResults',
              type: 'ToolResult[]',
              description: 'The tool results that have been generated.',
            },
            {
              name: 'warnings',
              type: 'Warning[] | undefined',
              description:
                'Warnings from the model provider (e.g. unsupported settings).',
            },
            {
              name: 'response',
              type: 'Response',
              isOptional: true,
              description: 'Response metadata.',
              properties: [
                {
                  type: 'Response',
                  parameters: [
                    {
                      name: 'id',
                      type: 'string',
                      description:
                        'The response identifier. The AI SDK uses the ID from the provider response when available, and generates an ID otherwise.',
                    },
                    {
                      name: 'modelId',
                      type: 'string',
                      description:
                        'The model that was used to generate the response. The AI SDK uses the response model from the provider response when available, and the model from the function call otherwise.',
                    },
                    {
                      name: 'timestamp',
                      type: 'Date',
                      description:
                        'The timestamp of the response. The AI SDK uses the response timestamp from the provider response when available, and creates a timestamp otherwise.',
                    },
                    {
                      name: 'headers',
                      isOptional: true,
                      type: 'Record<string, string>',
                      description: 'Optional response headers.',
                    },
                    {
                      name: 'messages',
                      type: 'Array<ResponseMessage>',
                      description:
                        'The response messages that were generated during the call. It consists of an assistant message, potentially containing tool calls.  When there are tool results, there is an additional tool message with the tool results that are available. If there are tools that do not have execute functions, they are not included in the tool results and need to be added separately.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'steps',
              type: 'Array<StepResult>',
              description:
                'Response information for every step. You can use this to get information about intermediate steps, such as the tool calls or the response headers.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              description: 'The experimental context.',
            },
          ],
        },
      ],
    },
    {
      name: 'onAbort',
      type: '(event: OnAbortResult) => Promise<void> | void',
      isOptional: true,
      description:
        'Callback that is called when a stream is aborted via AbortSignal. You can use it to perform cleanup operations.',
      properties: [
        {
          type: 'OnAbortResult',
          parameters: [
            {
              name: 'steps',
              type: 'Array<StepResult>',
              description: 'Details for all previously finished steps.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_onStart',
      type: '(event: OnStartEvent) => PromiseLike<void> | void',
      isOptional: true,
      description:
        'Callback that is called when the streamText operation begins, before any LLM calls are made. Errors thrown in this callback are silently caught and do not break the generation flow. Experimental (can break in patch releases).',
      properties: [
        {
          type: 'OnStartEvent',
          parameters: [
            {
              name: 'model',
              type: '{ provider: string; modelId: string }',
              description: 'The model being used for the generation.',
            },
            {
              name: 'system',
              type: 'string | SystemModelMessage | Array<SystemModelMessage> | undefined',
              description: 'The system message(s) provided to the model.',
            },
            {
              name: 'prompt',
              type: 'string | Array<ModelMessage> | undefined',
              description:
                'The prompt string or array of messages if using the prompt option.',
            },
            {
              name: 'messages',
              type: 'Array<ModelMessage> | undefined',
              description: 'The messages array if using the messages option.',
            },
            {
              name: 'tools',
              type: 'TOOLS | undefined',
              description: 'The tools available for this generation.',
            },
            {
              name: 'toolChoice',
              type: 'ToolChoice<TOOLS> | undefined',
              description: 'The tool choice strategy for this generation.',
            },
            {
              name: 'activeTools',
              type: 'Array<keyof TOOLS> | undefined',
              description:
                'Limits which tools are available for the model to call.',
            },
            {
              name: 'maxOutputTokens',
              type: 'number | undefined',
              description: 'Maximum number of tokens to generate.',
            },
            {
              name: 'temperature',
              type: 'number | undefined',
              description: 'Sampling temperature for generation.',
            },
            {
              name: 'topP',
              type: 'number | undefined',
              description: 'Top-p (nucleus) sampling parameter.',
            },
            {
              name: 'topK',
              type: 'number | undefined',
              description: 'Top-k sampling parameter.',
            },
            {
              name: 'presencePenalty',
              type: 'number | undefined',
              description: 'Presence penalty for generation.',
            },
            {
              name: 'frequencyPenalty',
              type: 'number | undefined',
              description: 'Frequency penalty for generation.',
            },
            {
              name: 'stopSequences',
              type: 'string[] | undefined',
              description: 'Sequences that will stop generation.',
            },
            {
              name: 'seed',
              type: 'number | undefined',
              description: 'Random seed for reproducible generation.',
            },
            {
              name: 'maxRetries',
              type: 'number',
              description: 'Maximum number of retries for failed requests.',
            },
            {
              name: 'timeout',
              type: 'number | { totalMs?: number; stepMs?: number; chunkMs?: number } | undefined',
              description:
                'Timeout configuration for the generation. Can be a number (milliseconds) or an object with totalMs, stepMs, chunkMs.',
            },
            {
              name: 'headers',
              type: 'Record<string, string | undefined> | undefined',
              description: 'Additional HTTP headers sent with the request.',
            },
            {
              name: 'providerOptions',
              type: 'ProviderOptions | undefined',
              description: 'Additional provider-specific options.',
            },
            {
              name: 'stopWhen',
              type: 'StopCondition<TOOLS> | Array<StopCondition<TOOLS>> | undefined',
              description:
                'Condition(s) for stopping the generation. When the condition is an array, any of the conditions can be met to stop.',
            },
            {
              name: 'output',
              type: 'OUTPUT | undefined',
              description:
                'The output specification for structured outputs, if configured.',
            },
            {
              name: 'abortSignal',
              type: 'AbortSignal | undefined',
              description: 'Abort signal for cancelling the operation.',
            },
            {
              name: 'include',
              type: '{ requestBody?: boolean } | undefined',
              description:
                'Settings for controlling what data is included in step results.',
            },
            {
              name: 'functionId',
              type: 'string | undefined',
              description:
                'Identifier from telemetry settings for grouping related operations.',
            },
            {
              name: 'metadata',
              type: 'Record<string, unknown> | undefined',
              description: 'Additional metadata passed to the generation.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              description:
                'User-defined context object that flows through the entire generation lifecycle.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_onStepStart',
      type: '(event: OnStepStartEvent) => PromiseLike<void> | void',
      isOptional: true,
      description:
        'Callback that is called when a step (LLM call) begins, before the provider is called. Errors thrown in this callback are silently caught and do not break the generation flow. Experimental (can break in patch releases).',
      properties: [
        {
          type: 'OnStepStartEvent',
          parameters: [
            {
              name: 'stepNumber',
              type: 'number',
              description: 'Zero-based index of the current step.',
            },
            {
              name: 'model',
              type: '{ provider: string; modelId: string }',
              description: 'The model being used for this step.',
            },
            {
              name: 'system',
              type: 'string | SystemModelMessage | Array<SystemModelMessage> | undefined',
              description: 'The system message for this step.',
            },
            {
              name: 'messages',
              type: 'Array<ModelMessage>',
              description:
                'The messages that will be sent to the model for this step. Uses the user-facing ModelMessage format. May be overridden by prepareStep.',
            },
            {
              name: 'tools',
              type: 'TOOLS | undefined',
              description: 'The tools available for this generation.',
            },
            {
              name: 'toolChoice',
              type: 'LanguageModelV3ToolChoice | undefined',
              description: 'The tool choice configuration for this step.',
            },
            {
              name: 'activeTools',
              type: 'Array<keyof TOOLS> | undefined',
              description: 'Limits which tools are available for this step.',
            },
            {
              name: 'steps',
              type: 'ReadonlyArray<StepResult<TOOLS>>',
              description:
                'Array of results from previous steps (empty for the first step).',
            },
            {
              name: 'providerOptions',
              type: 'ProviderOptions | undefined',
              description:
                'Additional provider-specific options for this step.',
            },
            {
              name: 'timeout',
              type: 'number | { totalMs?: number; stepMs?: number; chunkMs?: number } | undefined',
              description: 'Timeout configuration for the generation.',
            },
            {
              name: 'headers',
              type: 'Record<string, string | undefined> | undefined',
              description: 'Additional HTTP headers sent with the request.',
            },
            {
              name: 'stopWhen',
              type: 'StopCondition<TOOLS> | Array<StopCondition<TOOLS>> | undefined',
              description: 'Condition(s) for stopping the generation.',
            },
            {
              name: 'output',
              type: 'OUTPUT | undefined',
              description:
                'The output specification for structured outputs, if configured.',
            },
            {
              name: 'abortSignal',
              type: 'AbortSignal | undefined',
              description: 'Abort signal for cancelling the operation.',
            },
            {
              name: 'include',
              type: '{ requestBody?: boolean } | undefined',
              description:
                'Settings for controlling what data is included in step results.',
            },
            {
              name: 'functionId',
              type: 'string | undefined',
              description:
                'Identifier from telemetry settings for grouping related operations.',
            },
            {
              name: 'metadata',
              type: 'Record<string, unknown> | undefined',
              description: 'Additional metadata from telemetry settings.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              description:
                'User-defined context object. May be updated from prepareStep between steps.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_onToolCallStart',
      type: '(event: OnToolCallStartEvent) => PromiseLike<void> | void',
      isOptional: true,
      description:
        "Callback that is called right before a tool's execute function runs. Errors thrown in this callback are silently caught and do not break the generation flow. Experimental (can break in patch releases).",
      properties: [
        {
          type: 'OnToolCallStartEvent',
          parameters: [
            {
              name: 'stepNumber',
              type: 'number | undefined',
              description:
                'The zero-based index of the current step where this tool call occurs. May be undefined in streaming contexts.',
            },
            {
              name: 'model',
              type: '{ provider: string; modelId: string } | undefined',
              description:
                'Information about the model being used. May be undefined in streaming contexts.',
            },
            {
              name: 'toolCall',
              type: 'TypedToolCall<TOOLS>',
              description:
                'The full tool call object containing toolName, toolCallId, input, and metadata.',
            },
            {
              name: 'messages',
              type: 'Array<ModelMessage>',
              description:
                'The conversation messages available at tool execution time.',
            },
            {
              name: 'abortSignal',
              type: 'AbortSignal | undefined',
              description: 'Signal for cancelling the operation.',
            },
            {
              name: 'functionId',
              type: 'string | undefined',
              description:
                'Identifier from telemetry settings for grouping related operations.',
            },
            {
              name: 'metadata',
              type: 'Record<string, unknown> | undefined',
              description: 'Additional metadata from telemetry settings.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              description:
                'User-defined context object flowing through the generation.',
            },
          ],
        },
      ],
    },
    {
      name: 'experimental_onToolCallFinish',
      type: '(event: OnToolCallFinishEvent) => PromiseLike<void> | void',
      isOptional: true,
      description:
        "Callback that is called right after a tool's execute function completes (or errors). Uses a discriminated union on the `success` field: when `success: true`, `output` contains the tool result; when `success: false`, `error` contains the error. Errors thrown in this callback are silently caught and do not break the generation flow. Experimental (can break in patch releases).",
      properties: [
        {
          type: 'OnToolCallFinishEvent',
          parameters: [
            {
              name: 'stepNumber',
              type: 'number | undefined',
              description:
                'The zero-based index of the current step where this tool call occurred. May be undefined in streaming contexts.',
            },
            {
              name: 'model',
              type: '{ provider: string; modelId: string } | undefined',
              description:
                'Information about the model being used. May be undefined in streaming contexts.',
            },
            {
              name: 'toolCall',
              type: 'TypedToolCall<TOOLS>',
              description:
                'The full tool call object containing toolName, toolCallId, input, and metadata.',
            },
            {
              name: 'messages',
              type: 'Array<ModelMessage>',
              description:
                'The conversation messages available at tool execution time.',
            },
            {
              name: 'abortSignal',
              type: 'AbortSignal | undefined',
              description: 'Signal for cancelling the operation.',
            },
            {
              name: 'durationMs',
              type: 'number',
              description:
                'The wall-clock duration of the tool execution in milliseconds.',
            },
            {
              name: 'functionId',
              type: 'string | undefined',
              description:
                'Identifier from telemetry settings for grouping related operations.',
            },
            {
              name: 'metadata',
              type: 'Record<string, unknown> | undefined',
              description: 'Additional metadata from telemetry settings.',
            },
            {
              name: 'experimental_context',
              type: 'unknown',
              description:
                'User-defined context object flowing through the generation.',
            },
            {
              name: 'success',
              type: 'boolean',
              description:
                'Discriminator indicating whether the tool call succeeded. When true, output is available. When false, error is available.',
            },
            {
              name: 'output',
              type: 'unknown',
              description:
                "The tool's return value (only present when `success: true`).",
            },
            {
              name: 'error',
              type: 'unknown',
              description:
                'The error that occurred during tool execution (only present when `success: false`).',
            },
          ],
        },
      ],
    },
  ]}
/>

### Returns

<PropertiesTable
  content={[
    {
      name: 'content',
      type: 'Promise<Array<ContentPart<TOOLS>>>',
      description: 'The content that was generated in the last step. Automatically consumes the stream.',
    },
    {
      name: 'finishReason',
      type: "PromiseLike<'stop' | 'length' | 'content-filter' | 'tool-calls' | 'error' | 'other'>",
      description:
        'The reason why the generation finished. Automatically consumes the stream.',
    },
    {
      name: 'rawFinishReason',
      type: 'PromiseLike<string | undefined>',
      description:
        'The raw reason why the generation finished (from the provider).',
    },
    {
      name: 'usage',
      type: 'Promise<LanguageModelUsage>',
      description:
        'The token usage of the last step. Automatically consumes the stream.',
      properties: [
        {
          type: 'LanguageModelUsage',
          parameters: [
            {
              name: 'inputTokens',
              type: 'number | undefined',
              description: 'The number of input (prompt) tokens used.',
            },
            {
              name: 'outputTokens',
              type: 'number | undefined',
              description: 'The number of output (completion) tokens used.',
            },
            {
              name: 'totalTokens',
              type: 'number | undefined',
              description:
                'The total number of tokens as reported by the provider. This number might be different from the sum of inputTokens and outputTokens and e.g. include reasoning tokens or other overhead.',
            },
            {
              name: 'reasoningTokens',
              type: 'number | undefined',
              isOptional: true,
              description: 'The number of reasoning tokens used.',
            },
            {
              name: 'cachedInputTokens',
              type: 'number | undefined',
              isOptional: true,
              description: 'The number of cached input tokens.',
            },
          ],
        },
      ],
    },
    {
      name: 'totalUsage',
      type: 'Promise<LanguageModelUsage>',
      description: 'The total token usage of the generated response. When there are multiple steps, the usage is the sum of all step usages. Automatically consumes the stream.',
      properties: [
                  {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description: 'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description: 'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description: 'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description: 'Raw usage information from the provider. This is the provider\'s original usage information and may include additional fields.',
                    },
                  ],
                },
      ],
    },
    {
      name: 'providerMetadata',
      type: 'Promise<ProviderMetadata | undefined>',
      description:
        'Additional provider-specific metadata from the last step. Metadata is passed through from the provider to the AI SDK and enables provider-specific results that can be fully encapsulated in the provider.',
    },
    {
      name: 'text',
      type: 'Promise<string>',
      description:
        'The full text that has been generated. Automatically consumes the stream.',
    },
    {
      name: 'reasoning',
      type: 'Promise<Array<ReasoningOutput>>',
      description:
        'The full reasoning that the model has generated in the last step. Automatically consumes the stream.',
      properties: [
        {
          type: 'ReasoningOutput',
          parameters: [
            {
              name: 'type',
              type: "'reasoning'",
              description: 'The type of the message part.',
            },
            {
              name: 'text',
              type: 'string',
              description: 'The reasoning text.',
            },
            {
              name: 'providerMetadata',
              type: 'SharedV2ProviderMetadata',
              isOptional: true,
              description: 'Additional provider metadata for the source.',
            },
          ],
        },
      ],
    },
    {
      name: 'reasoningText',
      type: 'Promise<string | undefined>',
      description:
        'The reasoning text that the model has generated in the last step. Can be undefined if the model has only generated text. Automatically consumes the stream.',
    },
    {
      name: 'sources',
      type: 'Promise<Array<Source>>',
      description:
        'Sources that have been used as input to generate the response. For multi-step generation, the sources are accumulated from all steps. Automatically consumes the stream.',
      properties: [
        {
          type: 'Source',
          parameters: [
            {
              name: 'sourceType',
              type: "'url'",
              description:
                'A URL source. This is return by web search RAG models.',
            },
            {
              name: 'id',
              type: 'string',
              description: 'The ID of the source.',
            },
            {
              name: 'url',
              type: 'string',
              description: 'The URL of the source.',
            },
            {
              name: 'title',
              type: 'string',
              isOptional: true,
              description: 'The title of the source.',
            },
            {
              name: 'providerMetadata',
              type: 'SharedV2ProviderMetadata',
              isOptional: true,
              description: 'Additional provider metadata for the source.',
            },
          ],
        },
      ],
    },
    {
      name: 'files',
      type: 'Promise<Array<GeneratedFile>>',
      description:
        'Files that were generated in the final step. Automatically consumes the stream.',
      properties: [
        {
          type: 'GeneratedFile',
          parameters: [
            {
              name: 'base64',
              type: 'string',
              description: 'File as a base64 encoded string.',
            },
            {
              name: 'uint8Array',
              type: 'Uint8Array',
              description: 'File as a Uint8Array.',
            },
            {
              name: 'mediaType',
              type: 'string',
              description: 'The IANA media type of the file.',
            },
          ],
        },
      ],
    },
    {
      name: 'toolCalls',
      type: 'Promise<TypedToolCall<TOOLS>[]>',
      description:
        'The tool calls that have been executed. Automatically consumes the stream.',
    },
    {
      name: 'toolResults',
      type: 'Promise<TypedToolResult<TOOLS>[]>',
      description:
        'The tool results that have been generated. Resolved when the all tool executions are finished.',
    },
    {
      name: 'staticToolCalls',
      type: 'PromiseLike<Array<StaticToolCall<TOOLS>>>',
      description: 'The static tool calls that have been executed in the last step.',
    },
    {
      name: 'dynamicToolCalls',
      type: 'PromiseLike<Array<DynamicToolCall>>',
      description: 'The dynamic tool calls that have been executed in the last step.',
    },
    {
      name: 'staticToolResults',
      type: 'PromiseLike<Array<StaticToolResult<TOOLS>>>',
      description: 'The static tool results that have been generated in the last step.',
    },
    {
      name: 'dynamicToolResults',
      type: 'PromiseLike<Array<DynamicToolResult>>',
      description: 'The dynamic tool results that have been generated in the last step.',
    },
    {
      name: 'request',
      type: 'Promise<LanguageModelRequestMetadata>',
      description: 'Additional request information from the last step.',
      properties: [
        {
          type: 'LanguageModelRequestMetadata',
          parameters: [
            {
              name: 'body',
              type: 'string',
              description:
                'Raw request HTTP body that was sent to the provider API as a string (JSON should be stringified).',
            },
          ],
        },
      ],
    },
    {
      name: 'response',
      type: 'Promise<LanguageModelResponseMetadata & { messages: Array<ResponseMessage>; }>',
      description: 'Additional response information from the last step.',
      properties: [
        {
          type: 'LanguageModelResponseMetadata',
          parameters: [
            {
              name: 'id',
              type: 'string',
              description:
                'The response identifier. The AI SDK uses the ID from the provider response when available, and generates an ID otherwise.',
            },
            {
              name: 'modelId',
              type: 'string',
              description:
                'The model that was used to generate the response. The AI SDK uses the response model from the provider response when available, and the model from the function call otherwise.',
            },
            {
              name: 'timestamp',
              type: 'Date',
              description:
                'The timestamp of the response. The AI SDK uses the response timestamp from the provider response when available, and creates a timestamp otherwise.',
            },
            {
              name: 'headers',
              isOptional: true,
              type: 'Record<string, string>',
              description: 'Optional response headers.',
            },
            {
              name: 'messages',
              type: 'Array<ResponseMessage>',
              description:
                'The response messages that were generated during the call. It consists of an assistant message, potentially containing tool calls.  When there are tool results, there is an additional tool message with the tool results that are available. If there are tools that do not have execute functions, they are not included in the tool results and need to be added separately.',
            },
          ],
        },
      ],
    },
    {
      name: 'warnings',
      type: 'Promise<Warning[] | undefined>',
      description:
        'Warnings from the model provider (e.g. unsupported settings) for the first step.',
    },
    {
      name: 'steps',
      type: 'Promise<Array<StepResult>>',
      description:
        'Response information for every step. You can use this to get information about intermediate steps, such as the tool calls or the response headers.',
      properties: [
        {
          type: 'StepResult',
          parameters: [
            {
              name: 'stepType',
              type: '"initial" | "continue" | "tool-result"',
              description:
                'The type of step. The first step is always an "initial" step, and subsequent steps are either "continue" steps or "tool-result" steps.',
            },
            {
              name: 'text',
              type: 'string',
              description: 'The generated text by the model.',
            },
            {
              name: 'reasoning',
              type: 'string | undefined',
              description:
                'The reasoning text of the model (only available for some models).',
            },
            {
              name: 'sources',
              type: 'Array<Source>',
              description: 'Sources that have been used as input.',
              properties: [
                {
                  type: 'Source',
                  parameters: [
                    {
                      name: 'sourceType',
                      type: "'url'",
                      description:
                        'A URL source. This is return by web search RAG models.',
                    },
                    {
                      name: 'id',
                      type: 'string',
                      description: 'The ID of the source.',
                    },
                    {
                      name: 'url',
                      type: 'string',
                      description: 'The URL of the source.',
                    },
                    {
                      name: 'title',
                      type: 'string',
                      isOptional: true,
                      description: 'The title of the source.',
                    },
                    {
                      name: 'providerMetadata',
                      type: 'SharedV2ProviderMetadata',
                      isOptional: true,
                      description:
                        'Additional provider metadata for the source.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'files',
              type: 'Array<GeneratedFile>',
              description: 'Files that were generated in this step.',
              properties: [
                {
                  type: 'GeneratedFile',
                  parameters: [
                    {
                      name: 'base64',
                      type: 'string',
                      description: 'File as a base64 encoded string.',
                    },
                    {
                      name: 'uint8Array',
                      type: 'Uint8Array',
                      description: 'File as a Uint8Array.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'toolCalls',
              type: 'array',
              description: 'A list of tool calls made by the model.',
            },
            {
              name: 'toolResults',
              type: 'array',
              description:
                'A list of tool results returned as responses to earlier tool calls.',
            },
            {
              name: 'finishReason',
              type: "'stop' | 'length' | 'content-filter' | 'tool-calls' | 'error' | 'other'",
              description: 'The reason the model finished generating the text.',
            },
            {
              name: 'rawFinishReason',
              type: 'string | undefined',
              description:
                'The raw reason why the generation finished (from the provider).',
            },
            {
              name: 'usage',
              type: 'LanguageModelUsage',
              description: 'The token usage of the generated text.',
              properties: [
                {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description: 'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description: 'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description: 'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description: 'Raw usage information from the provider. This is the provider\'s original usage information and may include additional fields.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'request',
              type: 'RequestMetadata',
              isOptional: true,
              description: 'Request metadata.',
              properties: [
                {
                  type: 'RequestMetadata',
                  parameters: [
                    {
                      name: 'body',
                      type: 'string',
                      description:
                        'Raw request HTTP body that was sent to the provider API as a string (JSON should be stringified).',
                    },
                  ],
                },
              ],
            },
            {
              name: 'response',
              type: 'ResponseMetadata',
              isOptional: true,
              description: 'Response metadata.',
              properties: [
                {
                  type: 'ResponseMetadata',
                  parameters: [
                    {
                      name: 'id',
                      type: 'string',
                      description:
                        'The response identifier. The AI SDK uses the ID from the provider response when available, and generates an ID otherwise.',
                    },
                    {
                      name: 'modelId',
                      type: 'string',
                      description:
                        'The model that was used to generate the response. The AI SDK uses the response model from the provider response when available, and the model from the function call otherwise.',
                    },
                    {
                      name: 'timestamp',
                      type: 'Date',
                      description:
                        'The timestamp of the response. The AI SDK uses the response timestamp from the provider response when available, and creates a timestamp otherwise.',
                    },
                    {
                      name: 'headers',
                      isOptional: true,
                      type: 'Record<string, string>',
                      description: 'Optional response headers.',
                    },
                    {
                      name: 'messages',
                      type: 'Array<ResponseMessage>',
                      description:
                        'The response messages that were generated during the call. It consists of an assistant message, potentially containing tool calls.  When there are tool results, there is an additional tool message with the tool results that are available. If there are tools that do not have execute functions, they are not included in the tool results and need to be added separately.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'warnings',
              type: 'Warning[] | undefined',
              description:
                'Warnings from the model provider (e.g. unsupported settings).',
            },
            {
              name: 'isContinued',
              type: 'boolean',
              description:
                'True when there will be a continuation step with a continuation text.',
            },
            {
              name: 'providerMetadata',
              type: 'Record<string,JSONObject> | undefined',
              isOptional: true,
              description:
                'Optional metadata from the provider. The outer key is the provider name. The inner values are the metadata. Details depend on the provider.',
            },
          ],
        },
      ],
    },
    {
      name: 'textStream',
      type: 'AsyncIterableStream<string>',
      description:
        'A text stream that returns only the generated text deltas. You can use it as either an AsyncIterable or a ReadableStream. When an error occurs, the stream will throw the error.',
    },
    {
      name: 'fullStream',
      type: 'AsyncIterable<TextStreamPart<TOOLS>> & ReadableStream<TextStreamPart<TOOLS>>',
      description:
        'A stream with all events, including text deltas, tool calls, tool results, and errors. You can use it as either an AsyncIterable or a ReadableStream. Only errors that stop the stream, such as network errors, are thrown.',
      properties: [
        {
          type: 'TextStreamPart',
          description: 'Text content part from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'text'",
              description: 'The type to identify the object as text.',
            },
            {
              name: 'text',
              type: 'string',
              description: 'The text content.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          description: 'Reasoning content part from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'reasoning'",
              description: 'The type to identify the object as reasoning.',
            },
            {
              name: 'text',
              type: 'string',
              description: 'The reasoning text.',
            },
            {
              name: 'providerMetadata',
              type: 'ProviderMetadata',
              isOptional: true,
              description: 'Optional provider metadata for the reasoning.',
            },
          ],
        },

        {
          type: 'TextStreamPart',
          description: 'Source content part from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'source'",
              description: 'The type to identify the object as source.',
            },
            {
              name: 'sourceType',
              type: "'url'",
              description: 'A URL source. This is returned by web search RAG models.',
            },
            {
              name: 'id',
              type: 'string',
              description: 'The ID of the source.',
            },
            {
              name: 'url',
              type: 'string',
              description: 'The URL of the source.',
            },
            {
              name: 'title',
              type: 'string',
              isOptional: true,
              description: 'The title of the source.',
            },
            {
              name: 'providerMetadata',
              type: 'ProviderMetadata',
              isOptional: true,
              description: 'Additional provider metadata for the source.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          description: 'File content part from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'file'",
              description: 'The type to identify the object as file.',
            },
            {
              name: 'file',
              type: 'GeneratedFile',
              description: 'The file.',
              properties: [
                {
                  type: 'GeneratedFile',
                  parameters: [
                    {
                      name: 'base64',
                      type: 'string',
                      description: 'File as a base64 encoded string.',
                    },
                    {
                      name: 'uint8Array',
                      type: 'Uint8Array',
                      description: 'File as a Uint8Array.',
                    },
                    {
                      name: 'mediaType',
                      type: 'string',
                      description: 'The IANA media type of the file.',
                    },
                  ],
                },
              ],
            },
          ],
        },
        {
          type: 'TextStreamPart',
          description: 'Tool call from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'tool-call'",
              description: 'The type to identify the object as tool call.',
            },
            {
              name: 'toolCallId',
              type: 'string',
              description: 'The id of the tool call.',
            },
            {
              name: 'toolName',
              type: 'string',
              description:
                'The name of the tool, which typically would be the name of the function.',
            },
            {
              name: 'input',
              type: 'object based on tool parameters',
              description:
                'Parameters generated by the model to be used by the tool. The type is inferred from the tool definition.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'tool-call-streaming-start'",
              description:
                'Indicates the start of a tool call streaming. Only available when streaming tool calls.',
            },
            {
              name: 'toolCallId',
              type: 'string',
              description: 'The id of the tool call.',
            },
            {
              name: 'toolName',
              type: 'string',
              description:
                'The name of the tool, which typically would be the name of the function.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'tool-call-delta'",
              description:
                'The type to identify the object as tool call delta. Only available when streaming tool calls.',
            },
            {
              name: 'toolCallId',
              type: 'string',
              description: 'The id of the tool call.',
            },
            {
              name: 'toolName',
              type: 'string',
              description:
                'The name of the tool, which typically would be the name of the function.',
            },
            {
              name: 'argsTextDelta',
              type: 'string',
              description: 'The text delta of the tool call arguments.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          description: 'Tool result from ContentPart<TOOLS>',
          parameters: [
            {
              name: 'type',
              type: "'tool-result'",
              description: 'The type to identify the object as tool result.',
            },
            {
              name: 'toolCallId',
              type: 'string',
              description: 'The id of the tool call.',
            },
            {
              name: 'toolName',
              type: 'string',
              description:
                'The name of the tool, which typically would be the name of the function.',
            },
            {
              name: 'input',
              type: 'object based on tool parameters',
              description:
                'Parameters that were passed to the tool. The type is inferred from the tool definition.',
            },
            {
              name: 'output',
              type: 'tool execution return type',
              description:
                'The result returned by the tool after execution has completed. The type is inferred from the tool execute function return type.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'start-step'",
              description: 'Indicates the start of a new step in the stream.',
            },
            {
              name: 'request',
              type: 'LanguageModelRequestMetadata',
              description:
                'Information about the request that was sent to the language model provider.',
              properties: [
                {
                  type: 'LanguageModelRequestMetadata',
                  parameters: [
                    {
                      name: 'body',
                      type: 'string',
                      description:
                        'Raw request HTTP body that was sent to the provider API as a string.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'warnings',
              type: 'Warning[]',
              description:
                'Warnings from the model provider (e.g. unsupported settings).',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'finish-step'",
              description:
                'Indicates the end of the current step in the stream.',
            },
            {
              name: 'response',
              type: 'LanguageModelResponseMetadata',
              description:
                'Response metadata from the language model provider.',
              properties: [
                {
                  type: 'LanguageModelResponseMetadata',
                  parameters: [
                    {
                      name: 'id',
                      type: 'string',
                      description:
                        'The response identifier. The AI SDK uses the ID from the provider response when available, and generates an ID otherwise.',
                    },
                    {
                      name: 'modelId',
                      type: 'string',
                      description:
                        'The model that was used to generate the response. The AI SDK uses the response model from the provider response when available, and the model from the function call otherwise.',
                    },
                    {
                      name: 'timestamp',
                      type: 'Date',
                      description:
                        'The timestamp of the response. The AI SDK uses the response timestamp from the provider response when available, and creates a timestamp otherwise.',
                    },
                    {
                      name: 'headers',
                      type: 'Record<string, string>',
                      description: 'The response headers.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'usage',
              type: 'LanguageModelUsage',
              description: 'The token usage of the generated text.',
              properties: [
                 {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description: 'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description: 'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description: 'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description: 'Raw usage information from the provider. This is the provider\'s original usage information and may include additional fields.',
                    },
                  ],
                },
              ],
            },
            {
              name: 'finishReason',
              type: "'stop' | 'length' | 'content-filter' | 'tool-calls' | 'error' | 'other'",
              description: 'The reason the model finished generating the text.',
            },
            {
              name: 'rawFinishReason',
              type: 'string | undefined',
              description:
                'The raw reason why the generation finished (from the provider).',
            },
            {
              name: 'providerMetadata',
              type: 'ProviderMetadata | undefined',
              isOptional: true,
              description:
                'Optional metadata from the provider. The outer key is the provider name. The inner values are the metadata. Details depend on the provider.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'start'",
              description: 'Indicates the start of the stream.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'finish'",
              description: 'The type to identify the object as finish.',
            },
            {
              name: 'finishReason',
              type: "'stop' | 'length' | 'content-filter' | 'tool-calls' | 'error' | 'other'",
              description: 'The reason the model finished generating the text.',
            },
            {
              name: 'rawFinishReason',
              type: 'string | undefined',
              description:
                'The raw reason why the generation finished (from the provider).',
            },
            {
              name: 'totalUsage',
              type: 'LanguageModelUsage',
              description: 'The total token usage of the generated text.',
              properties: [
                {
                  type: 'LanguageModelUsage',
                  parameters: [
                    {
                      name: 'inputTokens',
                      type: 'number | undefined',
                      description: 'The total number of input (prompt) tokens used.',
                    },
                    {
                      name: 'inputTokenDetails',
                      type: 'LanguageModelInputTokenDetails',
                      description:
                        'Detailed information about the input (prompt) tokens. See also: cached tokens and non-cached tokens.',
                      properties: [
                        {
                          type: 'LanguageModelInputTokenDetails',
                          parameters: [
                            {
                              name: 'noCacheTokens',
                              type: 'number | undefined',
                              description:
                                'The number of non-cached input (prompt) tokens used.',
                            },
                            {
                              name: 'cacheReadTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens read.',
                            },
                            {
                              name: 'cacheWriteTokens',
                              type: 'number | undefined',
                              description:
                                'The number of cached input (prompt) tokens written.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'outputTokens',
                      type: 'number | undefined',
                      description: 'The number of total output (completion) tokens used.',
                    },
                    {
                      name: 'outputTokenDetails',
                      type: 'LanguageModelOutputTokenDetails',
                      description:
                        'Detailed information about the output (completion) tokens.',
                      properties: [
                        {
                          type: 'LanguageModelOutputTokenDetails',
                          parameters: [
                            {
                              name: 'textTokens',
                              type: 'number | undefined',
                              description: 'The number of text tokens used.',
                            },
                            {
                              name: 'reasoningTokens',
                              type: 'number | undefined',
                              description: 'The number of reasoning tokens used.',
                            },
                          ],
                        },
                      ],
                    },
                    {
                      name: 'totalTokens',
                      type: 'number | undefined',
                      description: 'The total number of tokens used.',
                    },
                    {
                      name: 'raw',
                      type: 'object | undefined',
                      isOptional: true,
                      description: 'Raw usage information from the provider. This is the provider\'s original usage information and may include additional fields.',
                    },
                  ],
                },
              ],
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'reasoning-part-finish'",
              description: 'Indicates the end of a reasoning part.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'error'",
              description: 'The type to identify the object as error.',
            },
            {
              name: 'error',
              type: 'unknown',
              description:
                'Describes the error that may have occurred during execution.',
            },
          ],
        },
        {
          type: 'TextStreamPart',
          parameters: [
            {
              name: 'type',
              type: "'abort'",
              description: 'The type to identify the object as abort.',
            },
            {
              name: 'reason',
              type: 'unknown',
              isOptional: true,
              description:
                'Optional abort reason (from AbortSignal.reason) when the stream is aborted.',
            },
          ],
        },
      ],
    },
    {
      name: 'partialOutputStream',
      type: 'AsyncIterableStream<PARTIAL_OUTPUT>',
      description:
        'A stream of partial parsed outputs. It uses the `output` specification. AsyncIterableStream is defined as AsyncIterable<T> & ReadableStream<T>.',
    },
    {
      name: 'elementStream',
      type: 'AsyncIterableStream<ELEMENT_OUTPUT>',
      description:
        'A stream of individual array elements as they complete. Only available when using `output: Output.array()`. Each element is complete and validated against the element schema. AsyncIterableStream is defined as AsyncIterable<T> & ReadableStream<T>.',
    },
    {
      name: 'output',
      type: 'Promise<COMPLETE_OUTPUT>',
      description:
        'The complete parsed output. It uses the `output` specification.',
    },
    {
      name: 'consumeStream',
      type: '(options?: ConsumeStreamOptions) => Promise<void>',
      description:
        'Consumes the stream without processing the parts. This is useful to force the stream to finish. If an error occurs, it is passed to the optional `onError` callback.',
      properties: [
        {
          type: 'ConsumeStreamOptions',
          parameters: [
            {
              name: 'onError',
              type: '(error: unknown) => void',
              isOptional: true,
              description: 'The error callback.',
            },
          ],
        },
      ],
    },
    {
      name: 'toUIMessageStream',
      type: '(options?: UIMessageStreamOptions) => AsyncIterableStream<UIMessageChunk>',
      description:
        'Converts the result to a UI message stream. Returns an AsyncIterableStream that can be used as both an AsyncIterable and a ReadableStream.',
      properties: [
        {
          type: 'UIMessageStreamOptions',
          parameters: [
            {
              name: 'originalMessages',
              type: 'UIMessage[]',
              isOptional: true,
              description: 'The original messages.',
            },
            {
              name: 'onFinish',
              type: '(options: { messages: UIMessage[]; isContinuation: boolean; responseMessage: UIMessage; isAborted: boolean; }) => void',
              isOptional: true,
              description: 'Callback function called when the stream finishes. Provides the updated list of UI messages, whether the response is a continuation, the response message, and whether the stream was aborted.',
            },
            {
              name: 'messageMetadata',
              type: '(options: { part: TextStreamPart<TOOLS> & { type: "start" | "finish" | "start-step" | "finish-step"; }; }) => unknown',
              isOptional: true,
              description: 'Extracts message metadata that will be sent to the client. Called on start and finish events.',
            },
            {
              name: 'sendReasoning',
              type: 'boolean',
              isOptional: true,
              description:
                'Send reasoning parts to the client. Defaults to false.',
            },
            {
              name: 'sendSources',
              type: 'boolean',
              isOptional: true,
              description:
                'Send source parts to the client. Defaults to false.',
            },
            {
              name: 'sendFinish',
              type: 'boolean',
              isOptional: true,
              description:
                'Send the finish event to the client. Defaults to true.',
            },
            {
              name: 'sendStart',
              type: 'boolean',
              isOptional: true,
              description:
                'Send the message start event to the client. Set to false if you are using additional streamText calls and the message start event has already been sent. Defaults to true.',
            },
            {
              name: 'onError',
              type: '(error: unknown) => string',
              isOptional: true,
              description:
                'Process an error, e.g. to log it. Returns error message to include in the data stream. Defaults to () => "An error occurred."',
            },
            {
              name: 'consumeSseStream',
              type: '(stream: ReadableStream) => Promise<void>',
              isOptional: true,
              description:
                'Function to consume the SSE stream. Required for proper abort handling in UI message streams. Use the `consumeStream` function from the AI SDK.',
            },
          ],
        },
      ],
    },
    {
      name: 'pipeUIMessageStreamToResponse',
      type: '(response: ServerResponse, options?: ResponseInit & UIMessageStreamOptions) => void',
      description:
        'Writes UI message stream output to a Node.js response-like object.',
      properties: [
        {
          type: 'ResponseInit & UIMessageStreamOptions',
          parameters: [
            {
              name: 'status',
              type: 'number',
              isOptional: true,
              description: 'The response status code.',
            },
            {
              name: 'statusText',
              type: 'string',
              isOptional: true,
              description: 'The response status text.',
            },
            {
              name: 'headers',
              type: 'HeadersInit',
              isOptional: true,
              description: 'The response headers.',
            },
          ],
        },
      ],
    },
    {
      name: 'pipeTextStreamToResponse',
      type: '(response: ServerResponse, init?: ResponseInit) => void',
      description:
        'Writes text delta output to a Node.js response-like object. It sets a `Content-Type` header to `text/plain; charset=utf-8` and writes each text delta as a separate chunk.',
      properties: [
        {
          type: 'ResponseInit',
          parameters: [
            {
              name: 'status',
              type: 'number',
              isOptional: true,
              description: 'The response status code.',
            },
            {
              name: 'statusText',
              type: 'string',
              isOptional: true,
              description: 'The response status text.',
            },
            {
              name: 'headers',
              type: 'Record<string, string>',
              isOptional: true,
              description: 'The response headers.',
            },
          ],
        },
      ],
    },
    {
      name: 'toUIMessageStreamResponse',
      type: '(options?: ResponseInit & UIMessageStreamOptions) => Response',
      description:
        'Converts the result to a streamed response object with a UI message stream.',
      properties: [
        {
          type: 'ResponseInit & UIMessageStreamOptions',
          parameters: [
            {
              name: 'status',
              type: 'number',
              isOptional: true,
              description: 'The response status code.',
            },
            {
              name: 'statusText',
              type: 'string',
              isOptional: true,
              description: 'The response status text.',
            },
            {
              name: 'headers',
              type: 'HeadersInit',
              isOptional: true,
              description: 'The response headers.',
            },
          ],
        },
      ],
    },
    {
      name: 'toTextStreamResponse',
      type: '(init?: ResponseInit) => Response',
      description:
        'Creates a simple text stream response. Each text delta is encoded as UTF-8 and sent as a separate chunk. Non-text-delta events are ignored.',
      properties: [
        {
          type: 'ResponseInit',
          parameters: [
            {
              name: 'status',
              type: 'number',
              isOptional: true,
              description: 'The response status code.',
            },
            {
              name: 'statusText',
              type: 'string',
              isOptional: true,
              description: 'The response status text.',
            },
            {
              name: 'headers',
              type: 'Record<string, string>',
              isOptional: true,
              description: 'The response headers.',
            },
          ],
        },
      ],
    },

]}
/>

## Examples

<ExampleLinks
  examples={[
    {
      title: 'Learn to stream text generated by a language model in Next.js',
      link: '/examples/next-app/basics/streaming-text-generation',
    },
    {
      title:
        'Learn to stream chat completions generated by a language model in Next.js',
      link: '/examples/next-app/chat/stream-chat-completion',
    },
    {
      title: 'Learn to stream text generated by a language model in Node.js',
      link: '/examples/node/generating-text/stream-text',
    },
    {
      title:
        'Learn to stream chat completions generated by a language model in Node.js',
      link: '/examples/node/generating-text/stream-text-with-chat-prompt',
    },
  ]}
/>
