## List Session Threads

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

List Session Threads

### Path Parameters

- `session_id: string`

### Query Parameters

- `limit: optional number`

  Maximum results per page. Defaults to 1000.

- `page: optional string`

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

### Header Parameters

- `"anthropic-beta": optional array of AnthropicBeta`

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

  - `string`

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

- `data: optional array of BetaManagedAgentsSessionThread`

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

  - `id: string`

    Unique identifier for this thread.

  - `agent: BetaManagedAgentsSessionThreadAgent`

    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`.

    - `id: string`

    - `description: string`

    - `mcp_servers: array of BetaManagedAgentsMCPServerURLDefinition`

      - `name: string`

      - `type: "url"`

        - `"url"`

      - `url: string`

    - `model: BetaManagedAgentsModelConfig`

      Model identifier and configuration.

      - `id: BetaManagedAgentsModel`

        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" or "claude-opus-4-8" or "claude-opus-4-7" or 8 more`

          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"`

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

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

            Frontier intelligence for long-running agents and coding

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

            Frontier intelligence for long-running agents and coding

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

            Most intelligent model for building agents and coding

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

            Best combination of speed and intelligence

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

            Fastest model with near-frontier intelligence

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

            Fastest model with near-frontier intelligence

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

            Premium model combining maximum intelligence with practical performance

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

            Premium model combining maximum intelligence with practical performance

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

            High-performance model for agents and coding

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

            High-performance model for agents and coding

        - `string`

      - `speed: optional "standard" or "fast"`

        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"`

        - `"fast"`

    - `name: string`

    - `skills: array of BetaManagedAgentsAnthropicSkill or BetaManagedAgentsCustomSkill`

      - `BetaManagedAgentsAnthropicSkill object { skill_id, type, version }`

        A resolved Anthropic-managed skill.

        - `skill_id: string`

        - `type: "anthropic"`

          - `"anthropic"`

        - `version: string`

      - `BetaManagedAgentsCustomSkill object { skill_id, type, version }`

        A resolved user-created custom skill.

        - `skill_id: string`

        - `type: "custom"`

          - `"custom"`

        - `version: string`

    - `system: string`

    - `tools: array of BetaManagedAgentsAgentToolset20260401 or BetaManagedAgentsMCPToolset or BetaManagedAgentsCustomTool`

      - `BetaManagedAgentsAgentToolset20260401 object { configs, default_config, type }`

        - `configs: array of BetaManagedAgentsAgentToolConfig`

          - `enabled: boolean`

          - `name: "bash" or "edit" or "read" or 5 more`

            Built-in agent tool identifier.

            - `"bash"`

            - `"edit"`

            - `"read"`

            - `"write"`

            - `"glob"`

            - `"grep"`

            - `"web_fetch"`

            - `"web_search"`

          - `permission_policy: BetaManagedAgentsAlwaysAllowPolicy or BetaManagedAgentsAlwaysAskPolicy`

            Permission policy for tool execution.

            - `BetaManagedAgentsAlwaysAllowPolicy object { type }`

              Tool calls are automatically approved without user confirmation.

              - `type: "always_allow"`

                - `"always_allow"`

            - `BetaManagedAgentsAlwaysAskPolicy object { type }`

              Tool calls require user confirmation before execution.

              - `type: "always_ask"`

                - `"always_ask"`

        - `default_config: BetaManagedAgentsAgentToolsetDefaultConfig`

          Resolved default configuration for agent tools.

          - `enabled: boolean`

          - `permission_policy: BetaManagedAgentsAlwaysAllowPolicy or BetaManagedAgentsAlwaysAskPolicy`

            Permission policy for tool execution.

            - `BetaManagedAgentsAlwaysAllowPolicy object { type }`

              Tool calls are automatically approved without user confirmation.

            - `BetaManagedAgentsAlwaysAskPolicy object { type }`

              Tool calls require user confirmation before execution.

        - `type: "agent_toolset_20260401"`

          - `"agent_toolset_20260401"`

      - `BetaManagedAgentsMCPToolset object { configs, default_config, mcp_server_name, type }`

        - `configs: array of BetaManagedAgentsMCPToolConfig`

          - `enabled: boolean`

          - `name: string`

          - `permission_policy: BetaManagedAgentsAlwaysAllowPolicy or BetaManagedAgentsAlwaysAskPolicy`

            Permission policy for tool execution.

            - `BetaManagedAgentsAlwaysAllowPolicy object { type }`

              Tool calls are automatically approved without user confirmation.

            - `BetaManagedAgentsAlwaysAskPolicy object { type }`

              Tool calls require user confirmation before execution.

        - `default_config: BetaManagedAgentsMCPToolsetDefaultConfig`

          Resolved default configuration for all tools from an MCP server.

          - `enabled: boolean`

          - `permission_policy: BetaManagedAgentsAlwaysAllowPolicy or BetaManagedAgentsAlwaysAskPolicy`

            Permission policy for tool execution.

            - `BetaManagedAgentsAlwaysAllowPolicy object { type }`

              Tool calls are automatically approved without user confirmation.

            - `BetaManagedAgentsAlwaysAskPolicy object { type }`

              Tool calls require user confirmation before execution.

        - `mcp_server_name: string`

        - `type: "mcp_toolset"`

          - `"mcp_toolset"`

      - `BetaManagedAgentsCustomTool object { description, input_schema, name, type }`

        A custom tool as returned in API responses.

        - `description: string`

        - `input_schema: BetaManagedAgentsCustomToolInputSchema`

          JSON Schema for custom tool input parameters.

          - `type: "object"`

            - `"object"`

          - `properties: optional map[unknown]`

          - `required: optional array of string`

        - `name: string`

        - `type: "custom"`

          - `"custom"`

    - `type: "agent"`

      - `"agent"`

    - `version: number`

  - `archived_at: string`

    A timestamp in RFC 3339 format

  - `created_at: string`

    A timestamp in RFC 3339 format

  - `parent_thread_id: string`

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

  - `session_id: string`

    The session this thread belongs to.

  - `stats: BetaManagedAgentsSessionThreadStats`

    Timing statistics for a session thread.

    - `active_seconds: optional number`

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

    - `duration_seconds: optional number`

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

    - `startup_seconds: optional number`

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

  - `status: BetaManagedAgentsSessionThreadStatus`

    SessionThreadStatus enum

    - `"running"`

    - `"idle"`

    - `"rescheduling"`

    - `"terminated"`

  - `type: "session_thread"`

    - `"session_thread"`

  - `updated_at: string`

    A timestamp in RFC 3339 format

  - `usage: BetaManagedAgentsSessionThreadUsage`

    Cumulative token usage for a session thread across all turns.

    - `cache_creation: optional BetaManagedAgentsCacheCreationUsage`

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

      - `ephemeral_1h_input_tokens: optional number`

        Tokens used to create 1-hour ephemeral cache entries.

      - `ephemeral_5m_input_tokens: optional number`

        Tokens used to create 5-minute ephemeral cache entries.

    - `cache_read_input_tokens: optional number`

      Total tokens read from prompt cache.

    - `input_tokens: optional number`

      Total input tokens consumed across all turns.

    - `output_tokens: optional number`

      Total output tokens generated across all turns.

- `next_page: optional string`

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

### Example

```http
curl https://api.anthropic.com/v1/sessions/$SESSION_ID/threads \
    -H 'anthropic-version: 2023-06-01' \
    -H 'anthropic-beta: managed-agents-2026-04-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY"
```

#### 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="
}
```