Claude Platform Docs

Send Events

POST/v1/sessions/{session_id}/events

Send Events

Path parameters
session_id: string
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"
Body
events: array of BetaManagedAgentsEventParams

Events to send to the session.

One of the following:
BetaManagedAgentsUserMessageEventParams object{ content, type }

Parameters for sending a user message to the session.

BetaManagedAgentsUserInterruptEventParams object{ type, session_thread_id }

Parameters for sending an interrupt to pause the agent.

type: "user.interrupt"
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.

BetaManagedAgentsUserToolConfirmationEventParams object{ result, tool_use_id, type, deny_message }

Parameters for confirming or denying a tool execution request.

result: "allow" or "deny"

UserToolConfirmationResult enum

One of the following:
"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 stop_reason.event_ids field.

minLength1
maxLength128
type: "user.tool_confirmation"
deny_message: optional string or null

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

maxLength10000
BetaManagedAgentsUserCustomToolResultEventParams object{ custom_tool_use_id, type, content, is_error }

Parameters for providing the result of a custom tool execution.

BetaManagedAgentsUserDefineOutcomeEventParams object{ description, rubric, type, max_iterations }

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

BetaManagedAgentsUserToolResultEventParams object{ tool_use_id, type, content, is_error }

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.

BetaManagedAgentsSystemMessageEventParams object{ content, type }

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 of BetaManagedAgentsSystemContentBlock { text, type }

System content blocks to append. Text-only.

text: string

The text content.

minLength1
type: "text"
type: "system.message"
Returns
BetaManagedAgentsSendSessionEvents object{ data }

Events that were successfully sent to the session.

Send Events

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