## Send Events **post** `/v1/sessions/{session_id}/events` Send Events ### Path Parameters - `session_id: string` ### 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"` ### Body Parameters - `events: array of BetaManagedAgentsEventParams` Events to send to the `session`. - `BetaManagedAgentsUserMessageEventParams object { content, type }` Parameters for sending a user message to the session. - `content: array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock` Array of content blocks for the user message. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `text: string` The text content. - `type: "text"` - `"text"` - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `source: BetaManagedAgentsBase64ImageSource or BetaManagedAgentsURLImageSource or BetaManagedAgentsFileImageSource` Union type for image source variants. - `BetaManagedAgentsBase64ImageSource object { data, media_type, type }` 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 object { type, url }` Image referenced by URL. - `type: "url"` - `"url"` - `url: string` URL of the image to fetch. - `BetaManagedAgentsFileImageSource object { file_id, type }` Image referenced by file ID. - `file_id: string` ID of a previously uploaded file. - `type: "file"` - `"file"` - `type: "image"` - `"image"` - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `source: BetaManagedAgentsBase64DocumentSource or BetaManagedAgentsPlainTextDocumentSource or BetaManagedAgentsURLDocumentSource or BetaManagedAgentsFileDocumentSource` Union type for document source variants. - `BetaManagedAgentsBase64DocumentSource object { data, media_type, type }` 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 object { data, media_type, type }` 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 object { type, url }` Document referenced by URL. - `type: "url"` - `"url"` - `url: string` URL of the document to fetch. - `BetaManagedAgentsFileDocumentSource object { file_id, type }` Document referenced by file ID. - `file_id: string` ID of a previously uploaded file. - `type: "file"` - `"file"` - `type: "document"` - `"document"` - `context: optional string` Additional context about the document for the model. - `title: optional string` The title of the document. - `type: "user.message"` - `"user.message"` - `BetaManagedAgentsUserInterruptEventParams object { type, session_thread_id }` Parameters for sending an interrupt to pause the agent. - `type: "user.interrupt"` - `"user.interrupt"` - `session_thread_id: optional string` 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 - `"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: optional string` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. - `BetaManagedAgentsUserCustomToolResultEventParams object { custom_tool_use_id, type, content, is_error }` 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: optional array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock or BetaManagedAgentsSearchResultBlock` The result content returned by the tool. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `BetaManagedAgentsSearchResultBlock object { citations, content, source, 2 more }` 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 of 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: optional boolean` Whether the tool execution resulted in an error. - `BetaManagedAgentsUserDefineOutcomeEventParams object { description, rubric, type, max_iterations }` 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 or BetaManagedAgentsTextRubricParams` Rubric for grading the quality of an outcome. - `BetaManagedAgentsFileRubricParams object { file_id, type }` Rubric referenced by a file uploaded via the Files API. - `file_id: string` ID of the rubric file. - `type: "file"` - `"file"` - `BetaManagedAgentsTextRubricParams object { content, type }` 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: optional number` Eval→revision cycles before giving up. Default 3, max 20. - `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. - `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: optional array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock or BetaManagedAgentsSearchResultBlock` The result content returned by the tool. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `BetaManagedAgentsSearchResultBlock object { citations, content, source, 2 more }` A block containing a web search result. - `is_error: optional boolean` Whether the tool execution resulted in an error. - `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` System content blocks to append. Text-only. - `text: string` The text content. - `type: "text"` - `"text"` - `type: "system.message"` - `"system.message"` ### Returns - `BetaManagedAgentsSendSessionEvents object { data }` Events that were successfully sent to the session. - `data: optional array of BetaManagedAgentsUserMessageEvent or BetaManagedAgentsUserInterruptEvent or BetaManagedAgentsUserToolConfirmationEvent or 4 more` Sent events - `BetaManagedAgentsUserMessageEvent object { id, content, type, processed_at }` A user message event in the session conversation. - `id: string` Unique identifier for this event. - `content: array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock` Array of content blocks comprising the user message. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `text: string` The text content. - `type: "text"` - `"text"` - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `source: BetaManagedAgentsBase64ImageSource or BetaManagedAgentsURLImageSource or BetaManagedAgentsFileImageSource` Union type for image source variants. - `BetaManagedAgentsBase64ImageSource object { data, media_type, type }` 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 object { type, url }` Image referenced by URL. - `type: "url"` - `"url"` - `url: string` URL of the image to fetch. - `BetaManagedAgentsFileImageSource object { file_id, type }` Image referenced by file ID. - `file_id: string` ID of a previously uploaded file. - `type: "file"` - `"file"` - `type: "image"` - `"image"` - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `source: BetaManagedAgentsBase64DocumentSource or BetaManagedAgentsPlainTextDocumentSource or BetaManagedAgentsURLDocumentSource or BetaManagedAgentsFileDocumentSource` Union type for document source variants. - `BetaManagedAgentsBase64DocumentSource object { data, media_type, type }` 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 object { data, media_type, type }` 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 object { type, url }` Document referenced by URL. - `type: "url"` - `"url"` - `url: string` URL of the document to fetch. - `BetaManagedAgentsFileDocumentSource object { file_id, type }` Document referenced by file ID. - `file_id: string` ID of a previously uploaded file. - `type: "file"` - `"file"` - `type: "document"` - `"document"` - `context: optional string` Additional context about the document for the model. - `title: optional string` The title of the document. - `type: "user.message"` - `"user.message"` - `processed_at: optional string` A timestamp in RFC 3339 format - `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"` - `"user.interrupt"` - `processed_at: optional string` A timestamp in RFC 3339 format - `session_thread_id: optional string` 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. - `id: string` Unique identifier for this event. - `result: "allow" or "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: optional string` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. - `processed_at: optional string` A timestamp in RFC 3339 format - `session_thread_id: optional string` 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 object { id, custom_tool_use_id, type, 4 more }` 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: optional array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock or BetaManagedAgentsSearchResultBlock` The result content returned by the tool. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `BetaManagedAgentsSearchResultBlock object { citations, content, source, 2 more }` 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 of 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: optional boolean` Whether the tool execution resulted in an error. - `processed_at: optional string` A timestamp in RFC 3339 format - `session_thread_id: optional string` Routes this result to a subagent thread. Copy from the `agent.custom_tool_use` event's `session_thread_id`. - `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. - `id: string` Unique identifier for this event. - `description: string` What the agent should produce. Copied from the input event. - `max_iterations: number` 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 or BetaManagedAgentsTextRubric` Rubric for grading the quality of an outcome. - `BetaManagedAgentsFileRubric object { file_id, type }` Rubric referenced by a file uploaded via the Files API. - `file_id: string` ID of the rubric file. - `type: "file"` - `"file"` - `BetaManagedAgentsTextRubric object { content, type }` 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 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. - `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: optional array of BetaManagedAgentsTextBlock or BetaManagedAgentsImageBlock or BetaManagedAgentsDocumentBlock or BetaManagedAgentsSearchResultBlock` The result content returned by the tool. - `BetaManagedAgentsTextBlock object { text, type }` Regular text content. - `BetaManagedAgentsImageBlock object { source, type }` Image content specified directly as base64 data or as a reference via a URL. - `BetaManagedAgentsDocumentBlock object { source, type, context, title }` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `BetaManagedAgentsSearchResultBlock object { citations, content, source, 2 more }` A block containing a web search result. - `is_error: optional boolean` Whether the tool execution resulted in an error. - `processed_at: optional string` A timestamp in RFC 3339 format - `session_thread_id: optional string` Routes this result to a subagent thread. Copy from the `agent.tool_use` event's `session_thread_id`. - `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` System content blocks. Text-only. - `text: string` The text content. - `type: "text"` - `"text"` - `type: "system.message"` - `"system.message"` - `processed_at: optional string` A timestamp in RFC 3339 format ### Example ```http 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" } ] }' ``` #### 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" } ] } ```