## Send Events

`client.beta.sessions.events.send(stringsessionID, EventSendParamsparams, RequestOptionsoptions?): BetaManagedAgentsSendSessionEvents`

**post** `/v1/sessions/{session_id}/events`

Send Events

### Parameters

- `sessionID: string`

- `params: EventSendParams`

  - `events: Array<BetaManagedAgentsEventParams>`

    Body param: Events to send to the `session`.

    - `BetaManagedAgentsUserMessageEventParams`

      Parameters for sending a user message to the session.

      - `content: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock>`

        Array of content blocks for the user message.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

          - `text: string`

            The text content.

          - `type: "text"`

            - `"text"`

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

          - `source: BetaManagedAgentsBase64ImageSource | BetaManagedAgentsURLImageSource | BetaManagedAgentsFileImageSource`

            Union type for image source variants.

            - `BetaManagedAgentsBase64ImageSource`

              Base64-encoded image data.

              - `data: string`

                Base64-encoded image data.

              - `media_type: string`

                MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp").

              - `type: "base64"`

                - `"base64"`

            - `BetaManagedAgentsURLImageSource`

              Image referenced by URL.

              - `type: "url"`

                - `"url"`

              - `url: string`

                URL of the image to fetch.

            - `BetaManagedAgentsFileImageSource`

              Image referenced by file ID.

              - `file_id: string`

                ID of a previously uploaded file.

              - `type: "file"`

                - `"file"`

          - `type: "image"`

            - `"image"`

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

          - `source: BetaManagedAgentsBase64DocumentSource | BetaManagedAgentsPlainTextDocumentSource | BetaManagedAgentsURLDocumentSource | BetaManagedAgentsFileDocumentSource`

            Union type for document source variants.

            - `BetaManagedAgentsBase64DocumentSource`

              Base64-encoded document data.

              - `data: string`

                Base64-encoded document data.

              - `media_type: string`

                MIME type of the document (e.g., "application/pdf").

              - `type: "base64"`

                - `"base64"`

            - `BetaManagedAgentsPlainTextDocumentSource`

              Plain text document content.

              - `data: string`

                The plain text content.

              - `media_type: "text/plain"`

                MIME type of the text content. Must be "text/plain".

                - `"text/plain"`

              - `type: "text"`

                - `"text"`

            - `BetaManagedAgentsURLDocumentSource`

              Document referenced by URL.

              - `type: "url"`

                - `"url"`

              - `url: string`

                URL of the document to fetch.

            - `BetaManagedAgentsFileDocumentSource`

              Document referenced by file ID.

              - `file_id: string`

                ID of a previously uploaded file.

              - `type: "file"`

                - `"file"`

          - `type: "document"`

            - `"document"`

          - `context?: string | null`

            Additional context about the document for the model.

          - `title?: string | null`

            The title of the document.

      - `type: "user.message"`

        - `"user.message"`

    - `BetaManagedAgentsUserInterruptEventParams`

      Parameters for sending an interrupt to pause the agent.

      - `type: "user.interrupt"`

        - `"user.interrupt"`

      - `session_thread_id?: string | null`

        If absent, interrupts every non-archived thread in a multiagent session (or the primary alone in a single-agent session). If present, interrupts only the named thread.

    - `BetaManagedAgentsUserToolConfirmationEventParams`

      Parameters for confirming or denying a tool execution request.

      - `result: "allow" | "deny"`

        UserToolConfirmationResult enum

        - `"allow"`

        - `"deny"`

      - `tool_use_id: string`

        The id of the `agent.tool_use` or `agent.mcp_tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.tool_confirmation"`

        - `"user.tool_confirmation"`

      - `deny_message?: string | null`

        Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'.

    - `BetaManagedAgentsUserCustomToolResultEventParams`

      Parameters for providing the result of a custom tool execution.

      - `custom_tool_use_id: string`

        The id of the `agent.custom_tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.custom_tool_result"`

        - `"user.custom_tool_result"`

      - `content?: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock | BetaManagedAgentsSearchResultBlock>`

        The result content returned by the tool.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

        - `BetaManagedAgentsSearchResultBlock`

          A block containing a web search result.

          - `citations: BetaManagedAgentsSearchResultCitations`

            Citation settings for a search result.

            - `enabled: boolean`

              Whether citations are enabled for this search result.

          - `content: Array<BetaManagedAgentsSearchResultContent>`

            Array of text content blocks from the search result.

            - `text: string`

              The text content.

            - `type: "text"`

              - `"text"`

          - `source: string`

            The URL source of the search result.

          - `title: string`

            The title of the search result.

          - `type: "search_result"`

            - `"search_result"`

      - `is_error?: boolean | null`

        Whether the tool execution resulted in an error.

    - `BetaManagedAgentsUserDefineOutcomeEventParams`

      Parameters for defining an outcome the agent should work toward. The agent begins work on receipt.

      - `description: string`

        What the agent should produce. This is the task specification.

      - `rubric: BetaManagedAgentsFileRubricParams | BetaManagedAgentsTextRubricParams`

        Rubric for grading the quality of an outcome.

        - `BetaManagedAgentsFileRubricParams`

          Rubric referenced by a file uploaded via the Files API.

          - `file_id: string`

            ID of the rubric file.

          - `type: "file"`

            - `"file"`

        - `BetaManagedAgentsTextRubricParams`

          Rubric content provided inline as text.

          - `content: string`

            Rubric content. Plain text or markdown — the grader treats it as freeform text. Maximum 262144 characters.

          - `type: "text"`

            - `"text"`

      - `type: "user.define_outcome"`

        - `"user.define_outcome"`

      - `max_iterations?: number | null`

        Eval→revision cycles before giving up. Default 3, max 20.

    - `BetaManagedAgentsUserToolResultEventParams`

      Parameters for providing the result of an agent-toolset tool execution. Only valid on `self_hosted` environments, where sandbox-routed tools are executed by the client rather than the server.

      - `tool_use_id: string`

        The id of the `agent.tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.tool_result"`

        - `"user.tool_result"`

      - `content?: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock | BetaManagedAgentsSearchResultBlock>`

        The result content returned by the tool.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

        - `BetaManagedAgentsSearchResultBlock`

          A block containing a web search result.

      - `is_error?: boolean | null`

        Whether the tool execution resulted in an error.

    - `BetaManagedAgentsSystemMessageEventParams`

      Privileged context for the accompanying turn and all subsequent turns, appended to the session's system context as a `role: "system"` turn rather than replacing the top-level system prompt. At most one per request: it must be the final event and immediately follow the `user.message`, `user.tool_result`, or `user.custom_tool_result` it accompanies. Only supported on models that accept mid-conversation system messages.

      - `content: Array<BetaManagedAgentsSystemContentBlock>`

        System content blocks to append. Text-only.

        - `text: string`

          The text content.

        - `type: "text"`

          - `"text"`

      - `type: "system.message"`

        - `"system.message"`

  - `betas?: Array<AnthropicBeta>`

    Header param: Optional header to specify the beta version(s) you want to use.

    - `(string & {})`

    - `"message-batches-2024-09-24" | "prompt-caching-2024-07-31" | "computer-use-2024-10-22" | 25 more`

      - `"message-batches-2024-09-24"`

      - `"prompt-caching-2024-07-31"`

      - `"computer-use-2024-10-22"`

      - `"computer-use-2025-01-24"`

      - `"pdfs-2024-09-25"`

      - `"token-counting-2024-11-01"`

      - `"token-efficient-tools-2025-02-19"`

      - `"output-128k-2025-02-19"`

      - `"files-api-2025-04-14"`

      - `"mcp-client-2025-04-04"`

      - `"mcp-client-2025-11-20"`

      - `"dev-full-thinking-2025-05-14"`

      - `"interleaved-thinking-2025-05-14"`

      - `"code-execution-2025-05-22"`

      - `"extended-cache-ttl-2025-04-11"`

      - `"context-1m-2025-08-07"`

      - `"context-management-2025-06-27"`

      - `"model-context-window-exceeded-2025-08-26"`

      - `"skills-2025-10-02"`

      - `"fast-mode-2026-02-01"`

      - `"output-300k-2026-03-24"`

      - `"user-profiles-2026-03-24"`

      - `"advisor-tool-2026-03-01"`

      - `"managed-agents-2026-04-01"`

      - `"cache-diagnosis-2026-04-07"`

      - `"thinking-token-count-2026-05-13"`

      - `"server-side-fallback-2026-06-01"`

      - `"fallback-credit-2026-06-01"`

### Returns

- `BetaManagedAgentsSendSessionEvents`

  Events that were successfully sent to the session.

  - `data?: Array<BetaManagedAgentsUserMessageEvent | BetaManagedAgentsUserInterruptEvent | BetaManagedAgentsUserToolConfirmationEvent | 4 more>`

    Sent events

    - `BetaManagedAgentsUserMessageEvent`

      A user message event in the session conversation.

      - `id: string`

        Unique identifier for this event.

      - `content: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock>`

        Array of content blocks comprising the user message.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

          - `text: string`

            The text content.

          - `type: "text"`

            - `"text"`

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

          - `source: BetaManagedAgentsBase64ImageSource | BetaManagedAgentsURLImageSource | BetaManagedAgentsFileImageSource`

            Union type for image source variants.

            - `BetaManagedAgentsBase64ImageSource`

              Base64-encoded image data.

              - `data: string`

                Base64-encoded image data.

              - `media_type: string`

                MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp").

              - `type: "base64"`

                - `"base64"`

            - `BetaManagedAgentsURLImageSource`

              Image referenced by URL.

              - `type: "url"`

                - `"url"`

              - `url: string`

                URL of the image to fetch.

            - `BetaManagedAgentsFileImageSource`

              Image referenced by file ID.

              - `file_id: string`

                ID of a previously uploaded file.

              - `type: "file"`

                - `"file"`

          - `type: "image"`

            - `"image"`

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

          - `source: BetaManagedAgentsBase64DocumentSource | BetaManagedAgentsPlainTextDocumentSource | BetaManagedAgentsURLDocumentSource | BetaManagedAgentsFileDocumentSource`

            Union type for document source variants.

            - `BetaManagedAgentsBase64DocumentSource`

              Base64-encoded document data.

              - `data: string`

                Base64-encoded document data.

              - `media_type: string`

                MIME type of the document (e.g., "application/pdf").

              - `type: "base64"`

                - `"base64"`

            - `BetaManagedAgentsPlainTextDocumentSource`

              Plain text document content.

              - `data: string`

                The plain text content.

              - `media_type: "text/plain"`

                MIME type of the text content. Must be "text/plain".

                - `"text/plain"`

              - `type: "text"`

                - `"text"`

            - `BetaManagedAgentsURLDocumentSource`

              Document referenced by URL.

              - `type: "url"`

                - `"url"`

              - `url: string`

                URL of the document to fetch.

            - `BetaManagedAgentsFileDocumentSource`

              Document referenced by file ID.

              - `file_id: string`

                ID of a previously uploaded file.

              - `type: "file"`

                - `"file"`

          - `type: "document"`

            - `"document"`

          - `context?: string | null`

            Additional context about the document for the model.

          - `title?: string | null`

            The title of the document.

      - `type: "user.message"`

        - `"user.message"`

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

    - `BetaManagedAgentsUserInterruptEvent`

      An interrupt event that pauses agent execution and returns control to the user.

      - `id: string`

        Unique identifier for this event.

      - `type: "user.interrupt"`

        - `"user.interrupt"`

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

      - `session_thread_id?: string | null`

        If absent, interrupts every non-archived thread in a multiagent session (or the primary alone in a single-agent session). If present, interrupts only the named thread.

    - `BetaManagedAgentsUserToolConfirmationEvent`

      A tool confirmation event that approves or denies a pending tool execution.

      - `id: string`

        Unique identifier for this event.

      - `result: "allow" | "deny"`

        UserToolConfirmationResult enum

        - `"allow"`

        - `"deny"`

      - `tool_use_id: string`

        The id of the `agent.tool_use` or `agent.mcp_tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.tool_confirmation"`

        - `"user.tool_confirmation"`

      - `deny_message?: string | null`

        Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'.

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

      - `session_thread_id?: string | null`

        When set, the confirmation routes to this subagent's thread rather than the primary. Echo this from the `session_thread_id` on the `agent.tool_use` or `agent.mcp_tool_use` event that prompted the approval.

    - `BetaManagedAgentsUserCustomToolResultEvent`

      Event sent by the client providing the result of a custom tool execution.

      - `id: string`

        Unique identifier for this event.

      - `custom_tool_use_id: string`

        The id of the `agent.custom_tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.custom_tool_result"`

        - `"user.custom_tool_result"`

      - `content?: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock | BetaManagedAgentsSearchResultBlock>`

        The result content returned by the tool.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

        - `BetaManagedAgentsSearchResultBlock`

          A block containing a web search result.

          - `citations: BetaManagedAgentsSearchResultCitations`

            Citation settings for a search result.

            - `enabled: boolean`

              Whether citations are enabled for this search result.

          - `content: Array<BetaManagedAgentsSearchResultContent>`

            Array of text content blocks from the search result.

            - `text: string`

              The text content.

            - `type: "text"`

              - `"text"`

          - `source: string`

            The URL source of the search result.

          - `title: string`

            The title of the search result.

          - `type: "search_result"`

            - `"search_result"`

      - `is_error?: boolean | null`

        Whether the tool execution resulted in an error.

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

      - `session_thread_id?: string | null`

        Routes this result to a subagent thread. Copy from the `agent.custom_tool_use` event's `session_thread_id`.

    - `BetaManagedAgentsUserDefineOutcomeEvent`

      Echo of a `user.define_outcome` input event. Carries the server-generated `outcome_id` that subsequent `span.outcome_evaluation_*` events reference.

      - `id: string`

        Unique identifier for this event.

      - `description: string`

        What the agent should produce. Copied from the input event.

      - `max_iterations: number | null`

        Evaluate-then-revise cycles before giving up. Default 3, max 20.

      - `outcome_id: string`

        Server-generated `outc_` ID for this outcome. Referenced by `span.outcome_evaluation_*` events and the session's `outcome_evaluations` list.

      - `processed_at: string`

        A timestamp in RFC 3339 format

      - `rubric: BetaManagedAgentsFileRubric | BetaManagedAgentsTextRubric`

        Rubric for grading the quality of an outcome.

        - `BetaManagedAgentsFileRubric`

          Rubric referenced by a file uploaded via the Files API.

          - `file_id: string`

            ID of the rubric file.

          - `type: "file"`

            - `"file"`

        - `BetaManagedAgentsTextRubric`

          Rubric content provided inline as text.

          - `content: string`

            Rubric content. Plain text or markdown — the grader treats it as freeform text.

          - `type: "text"`

            - `"text"`

      - `type: "user.define_outcome"`

        - `"user.define_outcome"`

    - `BetaManagedAgentsUserToolResultEvent`

      Event sent by the client providing the result of an agent-toolset tool execution. Only valid on `self_hosted` environments, where sandbox-routed tools are executed by the client rather than the server.

      - `id: string`

        Unique identifier for this event.

      - `tool_use_id: string`

        The id of the `agent.tool_use` event this result corresponds to, which can be found in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field.

      - `type: "user.tool_result"`

        - `"user.tool_result"`

      - `content?: Array<BetaManagedAgentsTextBlock | BetaManagedAgentsImageBlock | BetaManagedAgentsDocumentBlock | BetaManagedAgentsSearchResultBlock>`

        The result content returned by the tool.

        - `BetaManagedAgentsTextBlock`

          Regular text content.

        - `BetaManagedAgentsImageBlock`

          Image content specified directly as base64 data or as a reference via a URL.

        - `BetaManagedAgentsDocumentBlock`

          Document content, either specified directly as base64 data, as text, or as a reference via a URL.

        - `BetaManagedAgentsSearchResultBlock`

          A block containing a web search result.

      - `is_error?: boolean | null`

        Whether the tool execution resulted in an error.

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

      - `session_thread_id?: string | null`

        Routes this result to a subagent thread. Copy from the `agent.tool_use` event's `session_thread_id`.

    - `BetaManagedAgentsSystemMessageEvent`

      A mid-conversation system message event. Carries system-role content that is appended to the session as a `role: "system"` turn.

      - `id: string`

        Unique identifier for this event.

      - `content: Array<BetaManagedAgentsSystemContentBlock>`

        System content blocks. Text-only.

        - `text: string`

          The text content.

        - `type: "text"`

          - `"text"`

      - `type: "system.message"`

        - `"system.message"`

      - `processed_at?: string | null`

        A timestamp in RFC 3339 format

### Example

```typescript
import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  apiKey: process.env['ANTHROPIC_API_KEY'], // This is the default and can be omitted
});

const betaManagedAgentsSendSessionEvents = await client.beta.sessions.events.send(
  'sesn_011CZkZAtmR3yMPDzynEDxu7',
  {
    events: [
      { content: [{ text: 'Where is my order #1234?', type: 'text' }], type: 'user.message' },
    ],
  },
);

console.log(betaManagedAgentsSendSessionEvents.data);
```

#### Response

```json
{
  "data": [
    {
      "id": "sevt_011CZkZGOp0iBcp4kaQSihUmy",
      "content": [
        {
          "text": "Where is my order #1234?",
          "type": "text"
        }
      ],
      "type": "user.message",
      "processed_at": "2026-03-15T10:00:00Z"
    }
  ]
}
```
