Claude Platform Docs

List Session Thread Events

GET/v1/sessions/{session_id}/threads/{thread_id}/events

List Session Thread Events

Path parameters
session_id: string
thread_id: string
Query parameters
limit: optional number

Query parameter for limit

formatint32
page: optional string

Query parameter for page

Headers
"anthropic-beta": optional array of AnthropicBeta

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

One of the following:
string
"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 31 more
One of the following:
"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"
"user-profiles-2026-08-18"
"advisor-tool-2026-03-01"
"managed-agents-2026-04-01"
"cache-diagnosis-2026-04-07"
"dreaming-2026-04-21"
"thinking-token-count-2026-05-13"
"server-side-fallback-2026-06-01"
"server-side-fallback-2026-07-01"
"fallback-credit-2026-06-01"
"fallback-credit-2026-07-01"
"agent-memory-2026-07-22"
"mid-conversation-tool-changes-2026-07-01"
Returns
data: optional array of BetaManagedAgentsSessionEvent

Events for the thread, ordered by processed_at.

One of the following:
BetaManagedAgentsUserMessageEvent object{ id, content, type, processed_at }

A user message event in the session conversation.

BetaManagedAgentsUserInterruptEvent object{ id, type, processed_at, session_thread_id }

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

id: string

Unique identifier for this event.

type: "user.interrupt"
processed_at: optional string or null

A timestamp in RFC 3339 format

formatdate-time
session_thread_id: optional string or 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 object{ id, result, tool_use_id, 4 more }

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

BetaManagedAgentsUserCustomToolResultEvent object{ id, custom_tool_use_id, type, 4 more }

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

BetaManagedAgentsAgentCustomToolUseEvent object{ id, input, name, 3 more }

Event emitted when the agent calls a custom tool. The session goes idle until the client sends a user.custom_tool_result event with the result.

id: string

Unique identifier for this event.

input: map[unknown]

Input parameters for the tool call.

name: string

Name of the custom tool being called.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "agent.custom_tool_use"
session_thread_id: optional string or null

When set, this event was cross-posted from a subagent's thread to surface its custom tool use on the primary thread's stream. Empty on the thread's own events. Echo this on a user.custom_tool_result event to route the result back.

BetaManagedAgentsAgentMessageEvent object{ id, content, processed_at, type }

An agent response event in the session conversation.

BetaManagedAgentsAgentThinkingEvent object{ id, processed_at, type }

Indicates the agent is making forward progress via extended thinking. A progress signal, not a content carrier.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "agent.thinking"
BetaManagedAgentsAgentMCPToolUseEvent object{ id, input, mcp_server_name, 5 more }

Event emitted when the agent invokes a tool provided by an MCP server.

BetaManagedAgentsAgentMCPToolResultEvent object{ id, mcp_tool_use_id, processed_at, 3 more }

Event representing the result of an MCP tool execution.

BetaManagedAgentsAgentToolUseEvent object{ id, input, name, 4 more }

Event emitted when the agent invokes a built-in agent tool.

id: string

Unique identifier for this event.

input: map[unknown]

Input parameters for the tool call.

name: string

Name of the agent tool being used.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "agent.tool_use"
evaluated_permission: optional "allow" or "ask" or "deny"

AgentEvaluatedPermission enum

One of the following:
"allow"
"ask"
"deny"
session_thread_id: optional string or null

When set, this event was cross-posted from a subagent's thread to surface its permission request on the primary thread's stream. Empty on the thread's own events. Echo this on a user.tool_confirmation event to route the approval back.

BetaManagedAgentsAgentToolResultEvent object{ id, processed_at, tool_use_id, 3 more }

Event representing the result of an agent tool execution.

BetaManagedAgentsAgentThreadMessageReceivedEvent object{ id, content, from_session_thread_id, 3 more }

Delivery event written to the target thread's input stream when an agent-to-agent message arrives.

BetaManagedAgentsAgentThreadMessageSentEvent object{ id, content, processed_at, 3 more }

Observability event emitted to the sender's output stream when an agent-to-agent message is sent.

BetaManagedAgentsAgentThreadContextCompactedEvent object{ id, processed_at, type }

Indicates that context compaction (summarization) occurred during the session.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "agent.thread_context_compacted"
BetaManagedAgentsSessionErrorEvent object{ id, error, processed_at, type }

An error event indicating a problem occurred during session execution.

BetaManagedAgentsSessionStatusRescheduledEvent object{ id, processed_at, type }

Indicates the session is recovering from an error state and is rescheduled for execution.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "session.status_rescheduled"
BetaManagedAgentsSessionStatusRunningEvent object{ id, processed_at, type }

Indicates the session is actively running and the agent is working.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "session.status_running"
BetaManagedAgentsSessionStatusIdleEvent object{ id, processed_at, stop_reason, type }

Indicates the agent has paused and is awaiting user input.

BetaManagedAgentsSessionStatusTerminatedEvent object{ id, processed_at, type }

Indicates the session has terminated, either due to an error or completion.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "session.status_terminated"
BetaManagedAgentsSessionThreadCreatedEvent object{ id, agent_name, processed_at, 2 more }

Emitted when a subagent is spawned as a new thread. Written to the parent thread's output stream so clients observing the session see child creation.

id: string

Unique identifier for this event.

agent_name: string

Name of the callable agent the thread runs.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
session_thread_id: string

Public sthr_ ID of the newly created thread.

type: "session.thread_created"
BetaManagedAgentsSpanOutcomeEvaluationStartEvent object{ id, iteration, outcome_id, 2 more }

Emitted when an outcome evaluation cycle begins.

id: string

Unique identifier for this event.

iteration: number

0-indexed revision cycle. 0 is the first evaluation; 1 is the re-evaluation after the first revision; etc.

formatint32
outcome_id: string

The outc_ ID of the outcome being evaluated.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "span.outcome_evaluation_start"
BetaManagedAgentsSpanOutcomeEvaluationEndEvent object{ id, explanation, iteration, 6 more }

Emitted when an outcome evaluation cycle completes. Carries the verdict and aggregate token usage. A verdict of needs_revision means another evaluation cycle follows; satisfied, max_iterations_reached, failed, or interrupted are terminal — no further evaluation cycles follow.

BetaManagedAgentsSpanModelRequestStartEvent object{ id, processed_at, type }

Emitted when a model request is initiated by the agent.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "span.model_request_start"
BetaManagedAgentsSpanModelRequestEndEvent object{ id, is_error, model_request_start_id, 3 more }

Emitted when a model request completes.

BetaManagedAgentsSpanOutcomeEvaluationOngoingEvent object{ id, iteration, outcome_id, 2 more }

Periodic heartbeat emitted while an outcome evaluation cycle is in progress. Distinguishes 'evaluation is actively running' from 'evaluation is stuck' between the corresponding span.outcome_evaluation_start and span.outcome_evaluation_end events.

id: string

Unique identifier for this event.

iteration: number

0-indexed revision cycle, matching the corresponding span.outcome_evaluation_start.

formatint32
outcome_id: string

The outc_ ID of the outcome being evaluated.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "span.outcome_evaluation_ongoing"
BetaManagedAgentsUserDefineOutcomeEvent object{ id, description, max_iterations, 4 more }

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

BetaManagedAgentsSessionDeletedEvent object{ id, processed_at, type }

Emitted when a session has been deleted. Terminates any active event stream — no further events will be emitted for this session.

id: string

Unique identifier for this event.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
type: "session.deleted"
BetaManagedAgentsSessionThreadStatusRunningEvent object{ id, agent_name, processed_at, 2 more }

A session thread has begun executing. Emitted on the thread's own stream and cross-posted to the primary stream for child threads.

id: string

Unique identifier for this event.

agent_name: string

Name of the agent the thread runs.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
session_thread_id: string

Public sthr_ ID of the thread that started running.

type: "session.thread_status_running"
BetaManagedAgentsSessionThreadStatusIdleEvent object{ id, agent_name, processed_at, 3 more }

A session thread has yielded and is awaiting input. Emitted on the thread's own stream and cross-posted to the primary stream for child threads.

BetaManagedAgentsSessionThreadStatusTerminatedEvent object{ id, agent_name, processed_at, 2 more }

A session thread has terminated and will accept no further input. Emitted on the thread's own stream and cross-posted to the primary stream for child threads.

id: string

Unique identifier for this event.

agent_name: string

Name of the agent the thread runs.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
session_thread_id: string

Public sthr_ ID of the thread that terminated.

type: "session.thread_status_terminated"
BetaManagedAgentsUserToolResultEvent object{ id, tool_use_id, type, 4 more }

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.

BetaManagedAgentsSessionThreadStatusRescheduledEvent object{ id, agent_name, processed_at, 2 more }

A session thread hit a transient error and is retrying automatically. Emitted on the thread's own stream and cross-posted to the primary stream for child threads.

id: string

Unique identifier for this event.

agent_name: string

Name of the agent the thread runs.

processed_at: string

A timestamp in RFC 3339 format

formatdate-time
session_thread_id: string

Public sthr_ ID of the thread that is retrying.

type: "session.thread_status_rescheduled"
BetaManagedAgentsSessionUpdatedEvent object{ id, processed_at, type, 4 more }

Emitted when an UpdateSession request changed at least one field. Carries only the fields that changed; absent fields were not part of the update. The new configuration applies from the next turn.

BetaManagedAgentsSystemMessageEvent object{ id, content, type, processed_at }

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 of BetaManagedAgentsSystemContentBlock { text, type }

System content blocks. Text-only.

text: string

The text content.

minLength1
type: "text"
type: "system.message"
processed_at: optional string or null

A timestamp in RFC 3339 format

formatdate-time
BetaManagedAgentsSessionUsageEvent object{ id, processed_at, type, 2 more }

Periodic snapshot of the session's cumulative usage and tracked list cost.

next_page: optional string or null

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

List Session Thread Events

curl https://api.anthropic.com/v1/sessions/$SESSION_ID/threads/$THREAD_ID/events \
    -H 'anthropic-version: 2023-06-01' \
    -H 'anthropic-beta: managed-agents-2026-04-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY"
{
  "data": [
    {
      "id": "sevt_011CZkZGOp0iBcp4kaQSihUmy",
      "content": [
        {
          "text": "Where is my order #1234?",
          "type": "text"
        }
      ],
      "type": "user.message",
      "processed_at": "2026-03-15T10:00:00Z"
    }
  ],
  "next_page": "next_page"
}
Returns Examples
{
  "data": [
    {
      "id": "sevt_011CZkZGOp0iBcp4kaQSihUmy",
      "content": [
        {
          "text": "Where is my order #1234?",
          "type": "text"
        }
      ],
      "type": "user.message",
      "processed_at": "2026-03-15T10:00:00Z"
    }
  ],
  "next_page": "next_page"
}