## Send Events `BetaManagedAgentsSendSessionEvents Beta.Sessions.Events.Send(EventSendParamsparameters, CancellationTokencancellationToken = default)` **post** `/v1/sessions/{session_id}/events` Send Events ### Parameters - `EventSendParams parameters` - `required string sessionID` Path param: Path parameter session_id - `required IReadOnlyList events` Body param: Events to send to the `session`. - `class BetaManagedAgentsUserMessageEventParams:` Parameters for sending a user message to the session. - `required IReadOnlyList Content` Array of content blocks for the user message. - `class BetaManagedAgentsTextBlock:` Regular text content. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `required Source Source` Union type for image source variants. - `class BetaManagedAgentsBase64ImageSource:` Base64-encoded image data. - `required string Data` Base64-encoded image data. - `required string MediaType` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). - `required Type Type` - `"base64"Base64` - `class BetaManagedAgentsUrlImageSource:` Image referenced by URL. - `required Type Type` - `"url"Url` - `required string Url` URL of the image to fetch. - `class BetaManagedAgentsFileImageSource:` Image referenced by file ID. - `required string FileID` ID of a previously uploaded file. - `required Type Type` - `"file"File` - `required Type Type` - `"image"Image` - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `required Source Source` Union type for document source variants. - `class BetaManagedAgentsBase64DocumentSource:` Base64-encoded document data. - `required string Data` Base64-encoded document data. - `required string MediaType` MIME type of the document (e.g., "application/pdf"). - `required Type Type` - `"base64"Base64` - `class BetaManagedAgentsPlainTextDocumentSource:` Plain text document content. - `required string Data` The plain text content. - `required MediaType MediaType` MIME type of the text content. Must be "text/plain". - `"text/plain"TextPlain` - `required Type Type` - `"text"Text` - `class BetaManagedAgentsUrlDocumentSource:` Document referenced by URL. - `required Type Type` - `"url"Url` - `required string Url` URL of the document to fetch. - `class BetaManagedAgentsFileDocumentSource:` Document referenced by file ID. - `required string FileID` ID of a previously uploaded file. - `required Type Type` - `"file"File` - `required Type Type` - `"document"Document` - `string? Context` Additional context about the document for the model. - `string? Title` The title of the document. - `required Type Type` - `"user.message"UserMessage` - `class BetaManagedAgentsUserInterruptEventParams:` Parameters for sending an interrupt to pause the agent. - `required Type Type` - `"user.interrupt"UserInterrupt` - `string? SessionThreadID` 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. - `class BetaManagedAgentsUserToolConfirmationEventParams:` Parameters for confirming or denying a tool execution request. - `required Result Result` UserToolConfirmationResult enum - `"allow"Allow` - `"deny"Deny` - `required string ToolUseID` 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. - `required Type Type` - `"user.tool_confirmation"UserToolConfirmation` - `string? DenyMessage` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. - `class BetaManagedAgentsUserCustomToolResultEventParams:` Parameters for providing the result of a custom tool execution. - `required string CustomToolUseID` 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. - `required Type Type` - `"user.custom_tool_result"UserCustomToolResult` - `IReadOnlyList Content` The result content returned by the tool. - `class BetaManagedAgentsTextBlock:` Regular text content. - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `class BetaManagedAgentsSearchResultBlock:` A block containing a web search result. - `required BetaManagedAgentsSearchResultCitations Citations` Citation settings for a search result. - `required Boolean Enabled` Whether citations are enabled for this search result. - `required IReadOnlyList Content` Array of text content blocks from the search result. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `required string Source` The URL source of the search result. - `required string Title` The title of the search result. - `required Type Type` - `"search_result"SearchResult` - `Boolean? IsError` Whether the tool execution resulted in an error. - `class BetaManagedAgentsUserDefineOutcomeEventParams:` Parameters for defining an outcome the agent should work toward. The agent begins work on receipt. - `required string Description` What the agent should produce. This is the task specification. - `required Rubric Rubric` Rubric for grading the quality of an outcome. - `class BetaManagedAgentsFileRubricParams:` Rubric referenced by a file uploaded via the Files API. - `required string FileID` ID of the rubric file. - `required Type Type` - `"file"File` - `class BetaManagedAgentsTextRubricParams:` Rubric content provided inline as text. - `required string Content` Rubric content. Plain text or markdown — the grader treats it as freeform text. Maximum 262144 characters. - `required Type Type` - `"text"Text` - `required Type Type` - `"user.define_outcome"UserDefineOutcome` - `Int? MaxIterations` Eval→revision cycles before giving up. Default 3, max 20. - `class BetaManagedAgentsUserToolResultEventParams:` 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. - `required string ToolUseID` 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. - `required Type Type` - `"user.tool_result"UserToolResult` - `IReadOnlyList Content` The result content returned by the tool. - `class BetaManagedAgentsTextBlock:` Regular text content. - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `class BetaManagedAgentsSearchResultBlock:` A block containing a web search result. - `Boolean? IsError` Whether the tool execution resulted in an error. - `class BetaManagedAgentsSystemMessageEventParams:` 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. - `required IReadOnlyList Content` System content blocks to append. Text-only. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `required Type Type` - `"system.message"SystemMessage` - `IReadOnlyList 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 BetaManagedAgentsSendSessionEvents:` Events that were successfully sent to the session. - `IReadOnlyList Data` Sent events - `class BetaManagedAgentsUserMessageEvent:` A user message event in the session conversation. - `required string ID` Unique identifier for this event. - `required IReadOnlyList Content` Array of content blocks comprising the user message. - `class BetaManagedAgentsTextBlock:` Regular text content. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `required Source Source` Union type for image source variants. - `class BetaManagedAgentsBase64ImageSource:` Base64-encoded image data. - `required string Data` Base64-encoded image data. - `required string MediaType` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). - `required Type Type` - `"base64"Base64` - `class BetaManagedAgentsUrlImageSource:` Image referenced by URL. - `required Type Type` - `"url"Url` - `required string Url` URL of the image to fetch. - `class BetaManagedAgentsFileImageSource:` Image referenced by file ID. - `required string FileID` ID of a previously uploaded file. - `required Type Type` - `"file"File` - `required Type Type` - `"image"Image` - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `required Source Source` Union type for document source variants. - `class BetaManagedAgentsBase64DocumentSource:` Base64-encoded document data. - `required string Data` Base64-encoded document data. - `required string MediaType` MIME type of the document (e.g., "application/pdf"). - `required Type Type` - `"base64"Base64` - `class BetaManagedAgentsPlainTextDocumentSource:` Plain text document content. - `required string Data` The plain text content. - `required MediaType MediaType` MIME type of the text content. Must be "text/plain". - `"text/plain"TextPlain` - `required Type Type` - `"text"Text` - `class BetaManagedAgentsUrlDocumentSource:` Document referenced by URL. - `required Type Type` - `"url"Url` - `required string Url` URL of the document to fetch. - `class BetaManagedAgentsFileDocumentSource:` Document referenced by file ID. - `required string FileID` ID of a previously uploaded file. - `required Type Type` - `"file"File` - `required Type Type` - `"document"Document` - `string? Context` Additional context about the document for the model. - `string? Title` The title of the document. - `required Type Type` - `"user.message"UserMessage` - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format - `class BetaManagedAgentsUserInterruptEvent:` An interrupt event that pauses agent execution and returns control to the user. - `required string ID` Unique identifier for this event. - `required Type Type` - `"user.interrupt"UserInterrupt` - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format - `string? SessionThreadID` 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. - `class BetaManagedAgentsUserToolConfirmationEvent:` A tool confirmation event that approves or denies a pending tool execution. - `required string ID` Unique identifier for this event. - `required Result Result` UserToolConfirmationResult enum - `"allow"Allow` - `"deny"Deny` - `required string ToolUseID` 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. - `required Type Type` - `"user.tool_confirmation"UserToolConfirmation` - `string? DenyMessage` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format - `string? SessionThreadID` 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. - `class BetaManagedAgentsUserCustomToolResultEvent:` Event sent by the client providing the result of a custom tool execution. - `required string ID` Unique identifier for this event. - `required string CustomToolUseID` 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. - `required Type Type` - `"user.custom_tool_result"UserCustomToolResult` - `IReadOnlyList Content` The result content returned by the tool. - `class BetaManagedAgentsTextBlock:` Regular text content. - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `class BetaManagedAgentsSearchResultBlock:` A block containing a web search result. - `required BetaManagedAgentsSearchResultCitations Citations` Citation settings for a search result. - `required Boolean Enabled` Whether citations are enabled for this search result. - `required IReadOnlyList Content` Array of text content blocks from the search result. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `required string Source` The URL source of the search result. - `required string Title` The title of the search result. - `required Type Type` - `"search_result"SearchResult` - `Boolean? IsError` Whether the tool execution resulted in an error. - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format - `string? SessionThreadID` Routes this result to a subagent thread. Copy from the `agent.custom_tool_use` event's `session_thread_id`. - `class BetaManagedAgentsUserDefineOutcomeEvent:` Echo of a `user.define_outcome` input event. Carries the server-generated `outcome_id` that subsequent `span.outcome_evaluation_*` events reference. - `required string ID` Unique identifier for this event. - `required string Description` What the agent should produce. Copied from the input event. - `required Int? MaxIterations` Evaluate-then-revise cycles before giving up. Default 3, max 20. - `required string OutcomeID` Server-generated `outc_` ID for this outcome. Referenced by `span.outcome_evaluation_*` events and the session's `outcome_evaluations` list. - `required DateTimeOffset ProcessedAt` A timestamp in RFC 3339 format - `required Rubric Rubric` Rubric for grading the quality of an outcome. - `class BetaManagedAgentsFileRubric:` Rubric referenced by a file uploaded via the Files API. - `required string FileID` ID of the rubric file. - `required Type Type` - `"file"File` - `class BetaManagedAgentsTextRubric:` Rubric content provided inline as text. - `required string Content` Rubric content. Plain text or markdown — the grader treats it as freeform text. - `required Type Type` - `"text"Text` - `required Type Type` - `"user.define_outcome"UserDefineOutcome` - `class BetaManagedAgentsUserToolResultEvent:` 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. - `required string ID` Unique identifier for this event. - `required string ToolUseID` 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. - `required Type Type` - `"user.tool_result"UserToolResult` - `IReadOnlyList Content` The result content returned by the tool. - `class BetaManagedAgentsTextBlock:` Regular text content. - `class BetaManagedAgentsImageBlock:` Image content specified directly as base64 data or as a reference via a URL. - `class BetaManagedAgentsDocumentBlock:` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `class BetaManagedAgentsSearchResultBlock:` A block containing a web search result. - `Boolean? IsError` Whether the tool execution resulted in an error. - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format - `string? SessionThreadID` Routes this result to a subagent thread. Copy from the `agent.tool_use` event's `session_thread_id`. - `class BetaManagedAgentsSystemMessageEvent:` A mid-conversation system message event. Carries system-role content that is appended to the session as a `role: "system"` turn. - `required string ID` Unique identifier for this event. - `required IReadOnlyList Content` System content blocks. Text-only. - `required string Text` The text content. - `required Type Type` - `"text"Text` - `required Type Type` - `"system.message"SystemMessage` - `DateTimeOffset? ProcessedAt` A timestamp in RFC 3339 format ### Example ```csharp EventSendParams parameters = new() { SessionID = "sesn_011CZkZAtmR3yMPDzynEDxu7", Events = [ new BetaManagedAgentsUserMessageEventParams() { Content = [ new BetaManagedAgentsTextBlock() { Text = "Where is my order #1234?", Type = Type.Text, }, ], Type = Type.UserMessage, }, ], }; var betaManagedAgentsSendSessionEvents = await client.Beta.Sessions.Events.Send(parameters); Console.WriteLine(betaManagedAgentsSendSessionEvents); ``` #### 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" } ] } ```