## List Session Threads

`ThreadListPageResponse Beta.Sessions.Threads.List(ThreadListParamsparameters, CancellationTokencancellationToken = default)`

**get** `/v1/sessions/{session_id}/threads`

List Session Threads

### Parameters

- `ThreadListParams parameters`

  - `required string sessionID`

    Path param: Path parameter session_id

  - `Int limit`

    Query param: Maximum results per page. Defaults to 1000.

  - `string page`

    Query param: Opaque pagination cursor from a previous response's next_page. Forward-only.

  - `IReadOnlyList<AnthropicBeta> betas`

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

    - `"message-batches-2024-09-24"MessageBatches2024_09_24`

    - `"prompt-caching-2024-07-31"PromptCaching2024_07_31`

    - `"computer-use-2024-10-22"ComputerUse2024_10_22`

    - `"computer-use-2025-01-24"ComputerUse2025_01_24`

    - `"pdfs-2024-09-25"Pdfs2024_09_25`

    - `"token-counting-2024-11-01"TokenCounting2024_11_01`

    - `"token-efficient-tools-2025-02-19"TokenEfficientTools2025_02_19`

    - `"output-128k-2025-02-19"Output128k2025_02_19`

    - `"files-api-2025-04-14"FilesApi2025_04_14`

    - `"mcp-client-2025-04-04"McpClient2025_04_04`

    - `"mcp-client-2025-11-20"McpClient2025_11_20`

    - `"dev-full-thinking-2025-05-14"DevFullThinking2025_05_14`

    - `"interleaved-thinking-2025-05-14"InterleavedThinking2025_05_14`

    - `"code-execution-2025-05-22"CodeExecution2025_05_22`

    - `"extended-cache-ttl-2025-04-11"ExtendedCacheTtl2025_04_11`

    - `"context-1m-2025-08-07"Context1m2025_08_07`

    - `"context-management-2025-06-27"ContextManagement2025_06_27`

    - `"model-context-window-exceeded-2025-08-26"ModelContextWindowExceeded2025_08_26`

    - `"skills-2025-10-02"Skills2025_10_02`

    - `"fast-mode-2026-02-01"FastMode2026_02_01`

    - `"output-300k-2026-03-24"Output300k2026_03_24`

    - `"user-profiles-2026-03-24"UserProfiles2026_03_24`

    - `"advisor-tool-2026-03-01"AdvisorTool2026_03_01`

    - `"managed-agents-2026-04-01"ManagedAgents2026_04_01`

    - `"cache-diagnosis-2026-04-07"CacheDiagnosis2026_04_07`

    - `"thinking-token-count-2026-05-13"ThinkingTokenCount2026_05_13`

    - `"server-side-fallback-2026-06-01"ServerSideFallback2026_06_01`

    - `"fallback-credit-2026-06-01"FallbackCredit2026_06_01`

### Returns

- `class ThreadListPageResponse:`

  Paginated list of threads within a `session`.

  - `IReadOnlyList<BetaManagedAgentsSessionThread> Data`

    Threads in the session, primary first then children in spawn order.

    - `required string ID`

      Unique identifier for this thread.

    - `required BetaManagedAgentsSessionThreadAgent Agent`

      Resolved `agent` definition for a single `session_thread`. Snapshot of the agent at thread creation time. The multiagent roster is not repeated here; read it from `Session.agent`.

      - `required string ID`

      - `required string? Description`

      - `required IReadOnlyList<BetaManagedAgentsMcpServerUrlDefinition> McpServers`

        - `required string Name`

        - `required Type Type`

          - `"url"Url`

        - `required string Url`

      - `required BetaManagedAgentsModelConfig Model`

        Model identifier and configuration.

        - `required BetaManagedAgentsModel ID`

          The model that will power your agent.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `"claude-fable-5"ClaudeFable5`

            Next generation of intelligence for the hardest knowledge work and coding problems

          - `"claude-opus-4-8"ClaudeOpus4_8`

            Frontier intelligence for long-running agents and coding

          - `"claude-opus-4-7"ClaudeOpus4_7`

            Frontier intelligence for long-running agents and coding

          - `"claude-opus-4-6"ClaudeOpus4_6`

            Most intelligent model for building agents and coding

          - `"claude-sonnet-4-6"ClaudeSonnet4_6`

            Best combination of speed and intelligence

          - `"claude-haiku-4-5"ClaudeHaiku4_5`

            Fastest model with near-frontier intelligence

          - `"claude-haiku-4-5-20251001"ClaudeHaiku4_5_20251001`

            Fastest model with near-frontier intelligence

          - `"claude-opus-4-5"ClaudeOpus4_5`

            Premium model combining maximum intelligence with practical performance

          - `"claude-opus-4-5-20251101"ClaudeOpus4_5_20251101`

            Premium model combining maximum intelligence with practical performance

          - `"claude-sonnet-4-5"ClaudeSonnet4_5`

            High-performance model for agents and coding

          - `"claude-sonnet-4-5-20250929"ClaudeSonnet4_5_20250929`

            High-performance model for agents and coding

        - `Speed Speed`

          Inference speed mode. `fast` provides significantly faster output token generation at premium pricing. Not all models support `fast`; invalid combinations are rejected at create time.

          - `"standard"Standard`

          - `"fast"Fast`

      - `required string Name`

      - `required IReadOnlyList<Skill> Skills`

        - `class BetaManagedAgentsAnthropicSkill:`

          A resolved Anthropic-managed skill.

          - `required string SkillID`

          - `required Type Type`

            - `"anthropic"Anthropic`

          - `required string Version`

        - `class BetaManagedAgentsCustomSkill:`

          A resolved user-created custom skill.

          - `required string SkillID`

          - `required Type Type`

            - `"custom"Custom`

          - `required string Version`

      - `required string? System`

      - `required IReadOnlyList<Tool> Tools`

        - `class BetaManagedAgentsAgentToolset20260401:`

          - `required IReadOnlyList<BetaManagedAgentsAgentToolConfig> Configs`

            - `required Boolean Enabled`

            - `required Name Name`

              Built-in agent tool identifier.

              - `"bash"Bash`

              - `"edit"Edit`

              - `"read"Read`

              - `"write"Write`

              - `"glob"Glob`

              - `"grep"Grep`

              - `"web_fetch"WebFetch`

              - `"web_search"WebSearch`

            - `required PermissionPolicy PermissionPolicy`

              Permission policy for tool execution.

              - `class BetaManagedAgentsAlwaysAllowPolicy:`

                Tool calls are automatically approved without user confirmation.

                - `required Type Type`

                  - `"always_allow"AlwaysAllow`

              - `class BetaManagedAgentsAlwaysAskPolicy:`

                Tool calls require user confirmation before execution.

                - `required Type Type`

                  - `"always_ask"AlwaysAsk`

          - `required BetaManagedAgentsAgentToolsetDefaultConfig DefaultConfig`

            Resolved default configuration for agent tools.

            - `required Boolean Enabled`

            - `required PermissionPolicy PermissionPolicy`

              Permission policy for tool execution.

              - `class BetaManagedAgentsAlwaysAllowPolicy:`

                Tool calls are automatically approved without user confirmation.

              - `class BetaManagedAgentsAlwaysAskPolicy:`

                Tool calls require user confirmation before execution.

          - `required Type Type`

            - `"agent_toolset_20260401"AgentToolset20260401`

        - `class BetaManagedAgentsMcpToolset:`

          - `required IReadOnlyList<BetaManagedAgentsMcpToolConfig> Configs`

            - `required Boolean Enabled`

            - `required string Name`

            - `required PermissionPolicy PermissionPolicy`

              Permission policy for tool execution.

              - `class BetaManagedAgentsAlwaysAllowPolicy:`

                Tool calls are automatically approved without user confirmation.

              - `class BetaManagedAgentsAlwaysAskPolicy:`

                Tool calls require user confirmation before execution.

          - `required BetaManagedAgentsMcpToolsetDefaultConfig DefaultConfig`

            Resolved default configuration for all tools from an MCP server.

            - `required Boolean Enabled`

            - `required PermissionPolicy PermissionPolicy`

              Permission policy for tool execution.

              - `class BetaManagedAgentsAlwaysAllowPolicy:`

                Tool calls are automatically approved without user confirmation.

              - `class BetaManagedAgentsAlwaysAskPolicy:`

                Tool calls require user confirmation before execution.

          - `required string McpServerName`

          - `required Type Type`

            - `"mcp_toolset"McpToolset`

        - `class BetaManagedAgentsCustomTool:`

          A custom tool as returned in API responses.

          - `required string Description`

          - `required BetaManagedAgentsCustomToolInputSchema InputSchema`

            JSON Schema for custom tool input parameters.

            - `JsonElement Type "object"constant`

            - `IReadOnlyDictionary<string, JsonElement>? Properties`

            - `IReadOnlyList<string>? Required`

          - `required string Name`

          - `required Type Type`

            - `"custom"Custom`

      - `required Type Type`

        - `"agent"Agent`

      - `required Int Version`

    - `required DateTimeOffset? ArchivedAt`

      A timestamp in RFC 3339 format

    - `required DateTimeOffset CreatedAt`

      A timestamp in RFC 3339 format

    - `required string? ParentThreadID`

      Parent thread that spawned this thread. Null for the primary thread.

    - `required string SessionID`

      The session this thread belongs to.

    - `required BetaManagedAgentsSessionThreadStats? Stats`

      Timing statistics for a session thread.

      - `Double ActiveSeconds`

        Cumulative time in seconds the thread spent actively running. Excludes idle time.

      - `Double DurationSeconds`

        Elapsed time since thread creation in seconds. For archived threads, frozen at the final update.

      - `Double StartupSeconds`

        Time in seconds for the thread to begin running. Zero for child threads, which start immediately.

    - `required BetaManagedAgentsSessionThreadStatus Status`

      SessionThreadStatus enum

      - `"running"Running`

      - `"idle"Idle`

      - `"rescheduling"Rescheduling`

      - `"terminated"Terminated`

    - `required Type Type`

      - `"session_thread"SessionThread`

    - `required DateTimeOffset UpdatedAt`

      A timestamp in RFC 3339 format

    - `required BetaManagedAgentsSessionThreadUsage? Usage`

      Cumulative token usage for a session thread across all turns.

      - `BetaManagedAgentsCacheCreationUsage CacheCreation`

        Prompt-cache creation token usage broken down by cache lifetime.

        - `Int Ephemeral1hInputTokens`

          Tokens used to create 1-hour ephemeral cache entries.

        - `Int Ephemeral5mInputTokens`

          Tokens used to create 5-minute ephemeral cache entries.

      - `Int CacheReadInputTokens`

        Total tokens read from prompt cache.

      - `Int InputTokens`

        Total input tokens consumed across all turns.

      - `Int OutputTokens`

        Total output tokens generated across all turns.

  - `string? NextPage`

    Opaque cursor for the next page. Null when no more results.

### Example

```csharp
ThreadListParams parameters = new()
{
    SessionID = "sesn_011CZkZAtmR3yMPDzynEDxu7"
};

var page = await client.Beta.Sessions.Threads.List(parameters);
await foreach (var item in page.Paginate())
{
    Console.WriteLine(item);
}
```

#### Response

```json
{
  "data": [
    {
      "id": "sthr_011CZkZVWa6oIjw0rgXZpnBt",
      "agent": {
        "id": "agent_011CZkYqphY8vELVzwCUpqiQ",
        "description": "A focused research subagent.",
        "mcp_servers": [
          {
            "name": "example-mcp",
            "type": "url",
            "url": "https://example-server.modelcontextprotocol.io/sse"
          }
        ],
        "model": {
          "id": "claude-sonnet-4-6",
          "speed": "standard"
        },
        "name": "Researcher",
        "skills": [
          {
            "skill_id": "xlsx",
            "type": "anthropic",
            "version": "1"
          }
        ],
        "system": "You are a research subagent that gathers and summarises sources for the coordinating agent.",
        "tools": [
          {
            "configs": [
              {
                "enabled": true,
                "name": "bash",
                "permission_policy": {
                  "type": "always_allow"
                }
              }
            ],
            "default_config": {
              "enabled": true,
              "permission_policy": {
                "type": "always_ask"
              }
            },
            "type": "agent_toolset_20260401"
          }
        ],
        "type": "agent",
        "version": 1
      },
      "archived_at": null,
      "created_at": "2026-03-15T10:00:00Z",
      "parent_thread_id": null,
      "session_id": "sesn_011CZkZAtmR3yMPDzynEDxu7",
      "stats": {
        "active_seconds": 0,
        "duration_seconds": 0,
        "startup_seconds": 0
      },
      "status": "idle",
      "type": "session_thread",
      "updated_at": "2026-03-15T10:00:00Z",
      "usage": {
        "cache_creation": {
          "ephemeral_1h_input_tokens": 0,
          "ephemeral_5m_input_tokens": 0
        },
        "cache_read_input_tokens": 0,
        "input_tokens": 0,
        "output_tokens": 0
      }
    }
  ],
  "next_page": "page_MjAyNS0wNS0xNFQwMDowMDowMFo="
}
```
