--- title: Send Events url: https://platform.claude.com/docs/en/api/csharp/beta/sessions/events/send --- # Send Events `BetaManagedAgentsSendSessionEvents Beta.Sessions.Events.Send(parameters, cancellationToken = default)` **POST** `/v1/sessions/{session_id}/events` Send Events ## Parameters - `EventSendParams parameters` - `required string sessionID` (path parameter) - `required IReadOnlyList events` Events to send to the `session`. - `class BetaManagedAgentsUserMessageEventParams` Parameters for sending a user message to the session. - `JsonElement Type = "user.message"` - `required IReadOnlyList Content` Array of content blocks for the user message. - `class BetaManagedAgentsTextBlock` Regular text content. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `class BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `JsonElement Type = "image"` - `required Source Source` The source of the image data. - `class BetaManagedAgentsBase64ImageSource` Base64-encoded image data. - `JsonElement Type = "base64"` - `required string Data` Base64-encoded image data. minLength: 1 - `required string MediaType` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). minLength: 1 - `class BetaManagedAgentsUrlImageSource` Image referenced by URL. - `JsonElement Type = "url"` - `required string Url` URL of the image to fetch. minLength: 1 - `class BetaManagedAgentsFileImageSource` Image referenced by file ID. - `JsonElement Type = "file"` - `required string FileID` ID of a previously uploaded file. minLength: 1 - `class BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `JsonElement Type = "document"` - `required Source Source` The source of the document data. - `class BetaManagedAgentsBase64DocumentSource` Base64-encoded document data. - `JsonElement Type = "base64"` - `required string Data` Base64-encoded document data. minLength: 1 - `required string MediaType` MIME type of the document (e.g., "application/pdf"). minLength: 1 - `class BetaManagedAgentsPlainTextDocumentSource` Plain text document content. - `JsonElement Type = "text"` - `required string Data` The plain text content. minLength: 1 - `JsonElement MediaType = "text/plain"` MIME type of the text content. Must be "text/plain". - `class BetaManagedAgentsUrlDocumentSource` Document referenced by URL. - `JsonElement Type = "url"` - `required string Url` URL of the document to fetch. minLength: 1 - `class BetaManagedAgentsFileDocumentSource` Document referenced by file ID. - `JsonElement Type = "file"` - `required string FileID` ID of a previously uploaded file. minLength: 1 - `string? Context` Additional context about the document for the model. - `string? Title` The title of the document. - `class BetaManagedAgentsRedactedBlock` Placeholder for content withheld by Anthropic model policy. - `JsonElement Type = "redacted"` - `class BetaManagedAgentsUserInterruptEventParams` Parameters for sending an interrupt to pause the agent. - `JsonElement Type = "user.interrupt"` - `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. - `JsonElement Type = "user.tool_confirmation"` - `required Result Result` The confirmation result: 'allow' or 'deny'. - `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?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `string? DenyMessage` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. maxLength: 10000 - `class BetaManagedAgentsUserCustomToolResultEventParams` Parameters for providing the result of a custom tool execution. - `JsonElement Type = "user.custom_tool_result"` - `required string CustomToolUseID` The id of the `agent.custom_tool_use` event this result corresponds to. It is also listed in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `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. - `JsonElement Type = "search_result"` - `required BetaManagedAgentsSearchResultCitations Citations` Citation settings for this search result. - `required bool Enabled` Whether citations are enabled for this search result. - `required IReadOnlyList Content` Array of text content blocks from the search result. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `required string Source` The URL source of the search result. minLength: 1 - `required string Title` The title of the search result. minLength: 1 - `bool? 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. - `JsonElement Type = "user.define_outcome"` - `required string Description` What the agent should produce. This is the task specification. - `required Rubric Rubric` How to grade the outcome. Text or file reference. - `class BetaManagedAgentsFileRubricParams` Rubric referenced by a file uploaded via the Files API. - `JsonElement Type = "file"` - `required string FileID` ID of the rubric file. - `class BetaManagedAgentsTextRubricParams` Rubric content provided inline as text. - `JsonElement Type = "text"` - `required string Content` Rubric content. Plain text or markdown — the grader treats it as freeform text. Maximum 262144 characters. maxLength: 262144 - `int? MaxIterations` Eval→revision cycles before giving up. Default 3, max 20. format: int32 - `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. - `JsonElement Type = "user.tool_result"` - `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?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `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. - `bool? 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. - `JsonElement Type = "system.message"` - `required IReadOnlyList Content` System content blocks to append. Text-only. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `IReadOnlyList betas` (header parameter) This endpoint is in beta: requests must send `managed-agents-2026-04-01` in this header. - `MessageBatches2024_09_24("message-batches-2024-09-24")` - `PromptCaching2024_07_31("prompt-caching-2024-07-31")` - `ComputerUse2024_10_22("computer-use-2024-10-22")` - `ComputerUse2025_01_24("computer-use-2025-01-24")` - `Pdfs2024_09_25("pdfs-2024-09-25")` - `TokenCounting2024_11_01("token-counting-2024-11-01")` - `TokenEfficientTools2025_02_19("token-efficient-tools-2025-02-19")` - `Output128k2025_02_19("output-128k-2025-02-19")` - `FilesApi2025_04_14("files-api-2025-04-14")` - `McpClient2025_04_04("mcp-client-2025-04-04")` - `McpClient2025_11_20("mcp-client-2025-11-20")` - `DevFullThinking2025_05_14("dev-full-thinking-2025-05-14")` - `InterleavedThinking2025_05_14("interleaved-thinking-2025-05-14")` - `CodeExecution2025_05_22("code-execution-2025-05-22")` - `ExtendedCacheTtl2025_04_11("extended-cache-ttl-2025-04-11")` - `Context1m2025_08_07("context-1m-2025-08-07")` - `ContextManagement2025_06_27("context-management-2025-06-27")` - `ModelContextWindowExceeded2025_08_26("model-context-window-exceeded-2025-08-26")` - `Skills2025_10_02("skills-2025-10-02")` - `FastMode2026_02_01("fast-mode-2026-02-01")` - `Output300k2026_03_24("output-300k-2026-03-24")` - `UserProfiles2026_03_24("user-profiles-2026-03-24")` - `UserProfiles2026_08_18("user-profiles-2026-08-18")` - `UserProfiles2026_09_04("user-profiles-2026-09-04")` - `AdvisorTool2026_03_01("advisor-tool-2026-03-01")` - `ManagedAgents2026_04_01("managed-agents-2026-04-01")` - `CacheDiagnosis2026_04_07("cache-diagnosis-2026-04-07")` - `Dreaming2026_04_21("dreaming-2026-04-21")` - `ThinkingTokenCount2026_05_13("thinking-token-count-2026-05-13")` - `ServerSideFallback2026_06_01("server-side-fallback-2026-06-01")` - `ServerSideFallback2026_07_01("server-side-fallback-2026-07-01")` - `FallbackCredit2026_06_01("fallback-credit-2026-06-01")` - `FallbackCredit2026_07_01("fallback-credit-2026-07-01")` - `AgentMemory2026_07_22("agent-memory-2026-07-22")` - `MidConversationToolChanges2026_07_01("mid-conversation-tool-changes-2026-07-01")` - `Compact2026_01_12("compact-2026-01-12")` - `ComputerUse2025_11_24("computer-use-2025-11-24")` - `McpTunnels2026_06_22("mcp-tunnels-2026-06-22")` - `StructuredOutputs2025_11_13("structured-outputs-2025-11-13")` - `TaskBudgets2026_03_13("task-budgets-2026-03-13")` - `ThinkingDisplayUpdates2026_08_18("thinking-display-updates-2026-08-18")` - `CEUserManagement2026_07_13("ce-user-management-2026-07-13")` - `MidConversationOutputConfig2026_07_01("mid-conversation-output-config-2026-07-01")` - `ThinkingBindingControls2026_08_01("thinking-binding-controls-2026-08-01")` - `MidConversationSystemClearAt2026_08_21("mid-conversation-system-clear-at-2026-08-21")` - `Compact2026_09_04("compact-2026-09-04")` - `InlineTools2026_09_15("inline-tools-2026-09-15")` - `McpClient2026_09_15("mcp-client-2026-09-15")` - `CEPlugins2026_09_01("ce-plugins-2026-09-01")` - `SpendLimitReads2026_09_26("spend-limit-reads-2026-09-26")` - `TelemetryDestinations2026_08_11("telemetry-destinations-2026-08-11")` - `Webhooks2026_10_07("webhooks-2026-10-07")` - `MessageThreads2026_08_12("message-threads-2026-08-12")` - `AnalyticsUsageCost2026_08_24("analytics-usage-cost-2026-08-24")` - `ExperimentalClaudeTag2026_10_21("experimental-claude-tag-2026-10-21")` - `string workspaceID` (header parameter) Optional header to select the Workspace for this request. The value is a Workspace ID (for example, `wrkspc_011CZkZaBF1tNoB5wlCeusgy`). Only needed for credentials that can act on more than one Workspace. A credential that belongs to a specific Workspace may omit it; if sent, it must match that Workspace. ## 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. - `JsonElement Type = "user.message"` - `required string ID` Unique identifier for this event. - `required IReadOnlyList Content` Array of content blocks comprising the user message. - `class BetaManagedAgentsTextBlock` Regular text content. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `class BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `JsonElement Type = "image"` - `required Source Source` The source of the image data. - `class BetaManagedAgentsBase64ImageSource` Base64-encoded image data. - `JsonElement Type = "base64"` - `required string Data` Base64-encoded image data. minLength: 1 - `required string MediaType` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). minLength: 1 - `class BetaManagedAgentsUrlImageSource` Image referenced by URL. - `JsonElement Type = "url"` - `required string Url` URL of the image to fetch. minLength: 1 - `class BetaManagedAgentsFileImageSource` Image referenced by file ID. - `JsonElement Type = "file"` - `required string FileID` ID of a previously uploaded file. minLength: 1 - `class BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `JsonElement Type = "document"` - `required Source Source` The source of the document data. - `class BetaManagedAgentsBase64DocumentSource` Base64-encoded document data. - `JsonElement Type = "base64"` - `required string Data` Base64-encoded document data. minLength: 1 - `required string MediaType` MIME type of the document (e.g., "application/pdf"). minLength: 1 - `class BetaManagedAgentsPlainTextDocumentSource` Plain text document content. - `JsonElement Type = "text"` - `required string Data` The plain text content. minLength: 1 - `JsonElement MediaType = "text/plain"` MIME type of the text content. Must be "text/plain". - `class BetaManagedAgentsUrlDocumentSource` Document referenced by URL. - `JsonElement Type = "url"` - `required string Url` URL of the document to fetch. minLength: 1 - `class BetaManagedAgentsFileDocumentSource` Document referenced by file ID. - `JsonElement Type = "file"` - `required string FileID` ID of a previously uploaded file. minLength: 1 - `string? Context` Additional context about the document for the model. - `string? Title` The title of the document. - `class BetaManagedAgentsRedactedBlock` Placeholder for content withheld by Anthropic model policy. - `JsonElement Type = "redacted"` - `DateTimeOffset? ProcessedAt` Timestamp when the agent finished processing this message. format: date-time - `class BetaManagedAgentsUserInterruptEvent` An interrupt event that pauses agent execution and returns control to the user. - `JsonElement Type = "user.interrupt"` - `required string ID` Unique identifier for this event. - `DateTimeOffset? ProcessedAt` Timestamp when the interrupt was processed. format: date-time - `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. - `JsonElement Type = "user.tool_confirmation"` - `required string ID` Unique identifier for this event. - `required Result Result` The confirmation result: 'allow' or 'deny'. - `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?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `string? DenyMessage` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. maxLength: 10000 - `DateTimeOffset? ProcessedAt` Timestamp when the confirmation was processed. format: date-time - `string? SessionThreadID` Set by the server to the subagent thread this confirmation was routed to. Omitted when it was routed to the primary thread. - `class BetaManagedAgentsUserCustomToolResultEvent` Event sent by the client providing the result of a custom tool execution. - `JsonElement Type = "user.custom_tool_result"` - `required string ID` Unique identifier for this event. - `required string CustomToolUseID` The id of the `agent.custom_tool_use` event this result corresponds to. It is also listed in the last `session.status_idle` [event's](https://platform.claude.com/docs/en/api/beta/sessions/events/list?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `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. - `JsonElement Type = "search_result"` - `required BetaManagedAgentsSearchResultCitations Citations` Citation settings for this search result. - `required bool Enabled` Whether citations are enabled for this search result. - `required IReadOnlyList Content` Array of text content blocks from the search result. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `required string Source` The URL source of the search result. minLength: 1 - `required string Title` The title of the search result. minLength: 1 - `bool? IsError` Whether the tool execution resulted in an error. - `DateTimeOffset? ProcessedAt` Timestamp when this result was processed. format: date-time - `string? SessionThreadID` Set by the server to the subagent thread this result was routed to. Omitted when it was routed to the primary thread. - `class BetaManagedAgentsUserDefineOutcomeEvent` Echo of a `user.define_outcome` input event. Carries the server-generated `outcome_id` that subsequent `span.outcome_evaluation_*` events reference. - `JsonElement Type = "user.define_outcome"` - `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. format: int32 - `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` Timestamp when the outcome was accepted. format: date-time - `required Rubric Rubric` How to grade the outcome. File rubrics are currently resolved to their text content; clients should handle both variants. - `class BetaManagedAgentsFileRubric` Rubric referenced by a file uploaded via the Files API. - `JsonElement Type = "file"` - `required string FileID` ID of the rubric file. - `class BetaManagedAgentsTextRubric` Rubric content provided inline as text. - `JsonElement Type = "text"` - `required string Content` Rubric content. Plain text or markdown — the grader treats it as freeform text. - `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. - `JsonElement Type = "user.tool_result"` - `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?sdk_languages=csharp#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `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. - `bool? IsError` Whether the tool execution resulted in an error. - `DateTimeOffset? ProcessedAt` Timestamp when this result was processed. format: date-time - `string? SessionThreadID` Set by the server to the subagent thread this result was routed to. Omitted when it was routed to the primary thread. - `class BetaManagedAgentsSystemMessageEvent` A mid-conversation system message event. Carries system-role content that is appended to the session as a `role: "system"` turn. - `JsonElement Type = "system.message"` - `required string ID` Unique identifier for this event. - `required IReadOnlyList Content` System content blocks. Text-only. - `JsonElement Type = "text"` - `required string Text` The text content. minLength: 1 - `DateTimeOffset? ProcessedAt` Timestamp when this system message was processed. format: date-time ## Example ```csharp using System; using Anthropic.Models.Beta.Sessions.Events; EventSendParams parameters = new() { SessionID = "sesn_011CZkZAtmR3yMPDzynEDxu7", Events = [ new BetaManagedAgentsUserMessageEventParams( [ new BetaManagedAgentsTextBlock("Where is my order #1234?") ] ), ], }; var betaManagedAgentsSendSessionEvents = await client.Beta.Sessions.Events.Send(parameters); Console.WriteLine(betaManagedAgentsSendSessionEvents); ``` ### Response (200) ```json { "data": [ { "id": "sevt_011CZkZGPp1iBcp4kaQSihUm", "content": [ { "text": "Where is my order #1234?", "type": "text" } ], "type": "user.message", "processed_at": "2026-03-15T10:00:00Z" } ] } ```