--- title: Send Events url: https://platform.claude.com/docs/en/api/go/beta/sessions/events/send --- # Send Events `client.Beta.Sessions.Events.Send(ctx, sessionID, params) (*BetaManagedAgentsSendSessionEvents, error)` **POST** `/v1/sessions/{session_id}/events` Send Events ## Parameters - `sessionID string` (path parameter) - `params BetaSessionEventSendParams` - `Events []BetaManagedAgentsEventParamsUnion` Events to send to the `session`. - `type BetaManagedAgentsUserMessageEventParams` Parameters for sending a user message to the session. - `Type BetaManagedAgentsUserMessageEventParamsType` - `Content []BetaManagedAgentsUserMessageEventParamsContentUnion` Array of content blocks for the user message. - `type BetaManagedAgentsTextBlock` Regular text content. - `Type BetaManagedAgentsTextBlockType` - `Text string` The text content. minLength: 1 - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `Type BetaManagedAgentsImageBlockType` - `Source BetaManagedAgentsImageBlockSourceUnion` The source of the image data. - `type BetaManagedAgentsBase64ImageSource` Base64-encoded image data. - `Type BetaManagedAgentsBase64ImageSourceType` - `Data string` Base64-encoded image data. minLength: 1 - `MediaType string` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). minLength: 1 - `type BetaManagedAgentsURLImageSource` Image referenced by URL. - `Type BetaManagedAgentsURLImageSourceType` - `URL string` URL of the image to fetch. minLength: 1 - `type BetaManagedAgentsFileImageSource` Image referenced by file ID. - `Type BetaManagedAgentsFileImageSourceType` - `FileID string` ID of a previously uploaded file. minLength: 1 - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `Type BetaManagedAgentsDocumentBlockType` - `Source BetaManagedAgentsDocumentBlockSourceUnion` The source of the document data. - `type BetaManagedAgentsBase64DocumentSource` Base64-encoded document data. - `Type BetaManagedAgentsBase64DocumentSourceType` - `Data string` Base64-encoded document data. minLength: 1 - `MediaType string` MIME type of the document (e.g., "application/pdf"). minLength: 1 - `type BetaManagedAgentsPlainTextDocumentSource` Plain text document content. - `Type BetaManagedAgentsPlainTextDocumentSourceType` - `Data string` The plain text content. minLength: 1 - `MediaType BetaManagedAgentsPlainTextDocumentSourceMediaType` MIME type of the text content. Must be "text/plain". - `type BetaManagedAgentsURLDocumentSource` Document referenced by URL. - `Type BetaManagedAgentsURLDocumentSourceType` - `URL string` URL of the document to fetch. minLength: 1 - `type BetaManagedAgentsFileDocumentSource` Document referenced by file ID. - `Type BetaManagedAgentsFileDocumentSourceType` - `FileID string` ID of a previously uploaded file. minLength: 1 - `Context string Optional` Additional context about the document for the model. - `Title string Optional` The title of the document. - `type BetaManagedAgentsRedactedBlock` Placeholder for content withheld by Anthropic model policy. - `Type BetaManagedAgentsRedactedBlockType` - `type BetaManagedAgentsUserInterruptEventParams` Parameters for sending an interrupt to pause the agent. - `Type BetaManagedAgentsUserInterruptEventParamsType` - `SessionThreadID string Optional` 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. - `type BetaManagedAgentsUserToolConfirmationEventParams` Parameters for confirming or denying a tool execution request. - `Type BetaManagedAgentsUserToolConfirmationEventParamsType` - `Result BetaManagedAgentsUserToolConfirmationEventParamsResult` The confirmation result: 'allow' or 'deny'. - `const BetaManagedAgentsUserToolConfirmationEventParamsResultAllow BetaManagedAgentsUserToolConfirmationEventParamsResult = "allow"` - `const BetaManagedAgentsUserToolConfirmationEventParamsResultDeny BetaManagedAgentsUserToolConfirmationEventParamsResult = "deny"` - `ToolUseID 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?sdk_languages=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `DenyMessage string Optional` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. maxLength: 10000 - `type BetaManagedAgentsUserCustomToolResultEventParams` Parameters for providing the result of a custom tool execution. - `Type BetaManagedAgentsUserCustomToolResultEventParamsType` - `CustomToolUseID string` 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=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `Content []BetaManagedAgentsUserCustomToolResultEventParamsContentUnion Optional` The result content returned by the tool. - `type BetaManagedAgentsTextBlock` Regular text content. - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `type BetaManagedAgentsSearchResultBlock` A block containing a web search result. - `Type BetaManagedAgentsSearchResultBlockType` - `Citations BetaManagedAgentsSearchResultCitations` Citation settings for this search result. - `Enabled bool` Whether citations are enabled for this search result. - `Content []BetaManagedAgentsSearchResultContent` Array of text content blocks from the search result. - `Type BetaManagedAgentsSearchResultContentType` - `Text string` The text content. minLength: 1 - `Source string` The URL source of the search result. minLength: 1 - `Title string` The title of the search result. minLength: 1 - `IsError bool Optional` Whether the tool execution resulted in an error. - `type BetaManagedAgentsUserDefineOutcomeEventParams` Parameters for defining an outcome the agent should work toward. The agent begins work on receipt. - `Type BetaManagedAgentsUserDefineOutcomeEventParamsType` - `Description string` What the agent should produce. This is the task specification. - `Rubric BetaManagedAgentsUserDefineOutcomeEventParamsRubricUnion` How to grade the outcome. Text or file reference. - `type BetaManagedAgentsFileRubricParams` Rubric referenced by a file uploaded via the Files API. - `Type BetaManagedAgentsFileRubricParamsType` - `FileID string` ID of the rubric file. - `type BetaManagedAgentsTextRubricParams` Rubric content provided inline as text. - `Type BetaManagedAgentsTextRubricParamsType` - `Content string` Rubric content. Plain text or markdown — the grader treats it as freeform text. Maximum 262144 characters. maxLength: 262144 - `MaxIterations int64 Optional` Eval→revision cycles before giving up. Default 3, max 20. format: int32 - `type 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. - `Type BetaManagedAgentsUserToolResultEventParamsType` - `ToolUseID 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?sdk_languages=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. minLength: 1, maxLength: 128 - `Content []BetaManagedAgentsUserToolResultEventParamsContentUnion Optional` The result content returned by the tool. - `type BetaManagedAgentsTextBlock` Regular text content. - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `type BetaManagedAgentsSearchResultBlock` A block containing a web search result. - `IsError bool Optional` Whether the tool execution resulted in an error. - `type 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. - `Type BetaManagedAgentsSystemMessageEventParamsType` - `Content []BetaManagedAgentsSystemContentBlockParam` System content blocks to append. Text-only. - `Type BetaManagedAgentsSystemContentBlockType` - `Text string` The text content. minLength: 1 - `Betas []AnthropicBeta Optional` (header parameter) This endpoint is in beta: requests must send `managed-agents-2026-04-01` in this header. - `const AnthropicBetaMessageBatches2024_09_24 AnthropicBeta = "message-batches-2024-09-24"` - `const AnthropicBetaPromptCaching2024_07_31 AnthropicBeta = "prompt-caching-2024-07-31"` - `const AnthropicBetaComputerUse2024_10_22 AnthropicBeta = "computer-use-2024-10-22"` - `const AnthropicBetaComputerUse2025_01_24 AnthropicBeta = "computer-use-2025-01-24"` - `const AnthropicBetaPDFs2024_09_25 AnthropicBeta = "pdfs-2024-09-25"` - `const AnthropicBetaTokenCounting2024_11_01 AnthropicBeta = "token-counting-2024-11-01"` - `const AnthropicBetaTokenEfficientTools2025_02_19 AnthropicBeta = "token-efficient-tools-2025-02-19"` - `const AnthropicBetaOutput128k2025_02_19 AnthropicBeta = "output-128k-2025-02-19"` - `const AnthropicBetaFilesAPI2025_04_14 AnthropicBeta = "files-api-2025-04-14"` - `const AnthropicBetaMCPClient2025_04_04 AnthropicBeta = "mcp-client-2025-04-04"` - `const AnthropicBetaMCPClient2025_11_20 AnthropicBeta = "mcp-client-2025-11-20"` - `const AnthropicBetaDevFullThinking2025_05_14 AnthropicBeta = "dev-full-thinking-2025-05-14"` - `const AnthropicBetaInterleavedThinking2025_05_14 AnthropicBeta = "interleaved-thinking-2025-05-14"` - `const AnthropicBetaCodeExecution2025_05_22 AnthropicBeta = "code-execution-2025-05-22"` - `const AnthropicBetaExtendedCacheTTL2025_04_11 AnthropicBeta = "extended-cache-ttl-2025-04-11"` - `const AnthropicBetaContext1m2025_08_07 AnthropicBeta = "context-1m-2025-08-07"` - `const AnthropicBetaContextManagement2025_06_27 AnthropicBeta = "context-management-2025-06-27"` - `const AnthropicBetaModelContextWindowExceeded2025_08_26 AnthropicBeta = "model-context-window-exceeded-2025-08-26"` - `const AnthropicBetaSkills2025_10_02 AnthropicBeta = "skills-2025-10-02"` - `const AnthropicBetaFastMode2026_02_01 AnthropicBeta = "fast-mode-2026-02-01"` - `const AnthropicBetaOutput300k2026_03_24 AnthropicBeta = "output-300k-2026-03-24"` - `const AnthropicBetaUserProfiles2026_03_24 AnthropicBeta = "user-profiles-2026-03-24"` - `const AnthropicBetaUserProfiles2026_08_18 AnthropicBeta = "user-profiles-2026-08-18"` - `const AnthropicBetaUserProfiles2026_09_04 AnthropicBeta = "user-profiles-2026-09-04"` - `const AnthropicBetaAdvisorTool2026_03_01 AnthropicBeta = "advisor-tool-2026-03-01"` - `const AnthropicBetaManagedAgents2026_04_01 AnthropicBeta = "managed-agents-2026-04-01"` - `const AnthropicBetaCacheDiagnosis2026_04_07 AnthropicBeta = "cache-diagnosis-2026-04-07"` - `const AnthropicBetaDreaming2026_04_21 AnthropicBeta = "dreaming-2026-04-21"` - `const AnthropicBetaThinkingTokenCount2026_05_13 AnthropicBeta = "thinking-token-count-2026-05-13"` - `const AnthropicBetaServerSideFallback2026_06_01 AnthropicBeta = "server-side-fallback-2026-06-01"` - `const AnthropicBetaServerSideFallback2026_07_01 AnthropicBeta = "server-side-fallback-2026-07-01"` - `const AnthropicBetaFallbackCredit2026_06_01 AnthropicBeta = "fallback-credit-2026-06-01"` - `const AnthropicBetaFallbackCredit2026_07_01 AnthropicBeta = "fallback-credit-2026-07-01"` - `const AnthropicBetaAgentMemory2026_07_22 AnthropicBeta = "agent-memory-2026-07-22"` - `const AnthropicBetaMidConversationToolChanges2026_07_01 AnthropicBeta = "mid-conversation-tool-changes-2026-07-01"` - `const AnthropicBetaCompact2026_01_12 AnthropicBeta = "compact-2026-01-12"` - `const AnthropicBetaComputerUse2025_11_24 AnthropicBeta = "computer-use-2025-11-24"` - `const AnthropicBetaMCPTunnels2026_06_22 AnthropicBeta = "mcp-tunnels-2026-06-22"` - `const AnthropicBetaStructuredOutputs2025_11_13 AnthropicBeta = "structured-outputs-2025-11-13"` - `const AnthropicBetaTaskBudgets2026_03_13 AnthropicBeta = "task-budgets-2026-03-13"` - `const AnthropicBetaThinkingDisplayUpdates2026_08_18 AnthropicBeta = "thinking-display-updates-2026-08-18"` - `const AnthropicBetaCEUserManagement2026_07_13 AnthropicBeta = "ce-user-management-2026-07-13"` - `const AnthropicBetaMidConversationOutputConfig2026_07_01 AnthropicBeta = "mid-conversation-output-config-2026-07-01"` - `const AnthropicBetaThinkingBindingControls2026_08_01 AnthropicBeta = "thinking-binding-controls-2026-08-01"` - `const AnthropicBetaMidConversationSystemClearAt2026_08_21 AnthropicBeta = "mid-conversation-system-clear-at-2026-08-21"` - `const AnthropicBetaCompact2026_09_04 AnthropicBeta = "compact-2026-09-04"` - `const AnthropicBetaInlineTools2026_09_15 AnthropicBeta = "inline-tools-2026-09-15"` - `const AnthropicBetaMCPClient2026_09_15 AnthropicBeta = "mcp-client-2026-09-15"` - `const AnthropicBetaCEPlugins2026_09_01 AnthropicBeta = "ce-plugins-2026-09-01"` - `const AnthropicBetaSpendLimitReads2026_09_26 AnthropicBeta = "spend-limit-reads-2026-09-26"` - `const AnthropicBetaTelemetryDestinations2026_08_11 AnthropicBeta = "telemetry-destinations-2026-08-11"` - `WorkspaceID param.Opt[string] Optional` (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 - `type BetaManagedAgentsSendSessionEvents` Events that were successfully sent to the session. - `Data []BetaManagedAgentsSendSessionEventsDataUnion Optional` Sent events - `type BetaManagedAgentsUserMessageEvent` A user message event in the session conversation. - `Type BetaManagedAgentsUserMessageEventType` - `ID string` Unique identifier for this event. - `Content []BetaManagedAgentsUserMessageEventContentUnion` Array of content blocks comprising the user message. - `type BetaManagedAgentsTextBlock` Regular text content. - `Type BetaManagedAgentsTextBlockType` - `Text string` The text content. minLength: 1 - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `Type BetaManagedAgentsImageBlockType` - `Source BetaManagedAgentsImageBlockSourceUnion` The source of the image data. - `type BetaManagedAgentsBase64ImageSource` Base64-encoded image data. - `Type BetaManagedAgentsBase64ImageSourceType` - `Data string` Base64-encoded image data. minLength: 1 - `MediaType string` MIME type of the image (e.g., "image/png", "image/jpeg", "image/gif", "image/webp"). minLength: 1 - `type BetaManagedAgentsURLImageSource` Image referenced by URL. - `Type BetaManagedAgentsURLImageSourceType` - `URL string` URL of the image to fetch. minLength: 1 - `type BetaManagedAgentsFileImageSource` Image referenced by file ID. - `Type BetaManagedAgentsFileImageSourceType` - `FileID string` ID of a previously uploaded file. minLength: 1 - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `Type BetaManagedAgentsDocumentBlockType` - `Source BetaManagedAgentsDocumentBlockSourceUnion` The source of the document data. - `type BetaManagedAgentsBase64DocumentSource` Base64-encoded document data. - `Type BetaManagedAgentsBase64DocumentSourceType` - `Data string` Base64-encoded document data. minLength: 1 - `MediaType string` MIME type of the document (e.g., "application/pdf"). minLength: 1 - `type BetaManagedAgentsPlainTextDocumentSource` Plain text document content. - `Type BetaManagedAgentsPlainTextDocumentSourceType` - `Data string` The plain text content. minLength: 1 - `MediaType BetaManagedAgentsPlainTextDocumentSourceMediaType` MIME type of the text content. Must be "text/plain". - `type BetaManagedAgentsURLDocumentSource` Document referenced by URL. - `Type BetaManagedAgentsURLDocumentSourceType` - `URL string` URL of the document to fetch. minLength: 1 - `type BetaManagedAgentsFileDocumentSource` Document referenced by file ID. - `Type BetaManagedAgentsFileDocumentSourceType` - `FileID string` ID of a previously uploaded file. minLength: 1 - `Context string Optional` Additional context about the document for the model. - `Title string Optional` The title of the document. - `type BetaManagedAgentsRedactedBlock` Placeholder for content withheld by Anthropic model policy. - `Type BetaManagedAgentsRedactedBlockType` - `ProcessedAt Time Optional` Timestamp when the agent finished processing this message. format: date-time - `type BetaManagedAgentsUserInterruptEvent` An interrupt event that pauses agent execution and returns control to the user. - `Type BetaManagedAgentsUserInterruptEventType` - `ID string` Unique identifier for this event. - `ProcessedAt Time Optional` Timestamp when the interrupt was processed. format: date-time - `SessionThreadID string Optional` 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. - `type BetaManagedAgentsUserToolConfirmationEvent` A tool confirmation event that approves or denies a pending tool execution. - `Type BetaManagedAgentsUserToolConfirmationEventType` - `ID string` Unique identifier for this event. - `Result BetaManagedAgentsUserToolConfirmationEventResult` The confirmation result: 'allow' or 'deny'. - `const BetaManagedAgentsUserToolConfirmationEventResultAllow BetaManagedAgentsUserToolConfirmationEventResult = "allow"` - `const BetaManagedAgentsUserToolConfirmationEventResultDeny BetaManagedAgentsUserToolConfirmationEventResult = "deny"` - `ToolUseID 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?sdk_languages=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `DenyMessage string Optional` Optional message providing context for a 'deny' decision. Only allowed when result is 'deny'. maxLength: 10000 - `ProcessedAt Time Optional` Timestamp when the confirmation was processed. format: date-time - `SessionThreadID string Optional` Set by the server to the subagent thread this confirmation was routed to. Omitted when it was routed to the primary thread. - `type BetaManagedAgentsUserCustomToolResultEvent` Event sent by the client providing the result of a custom tool execution. - `Type BetaManagedAgentsUserCustomToolResultEventType` - `ID string` Unique identifier for this event. - `CustomToolUseID string` 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=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `Content []BetaManagedAgentsUserCustomToolResultEventContentUnion Optional` The result content returned by the tool. - `type BetaManagedAgentsTextBlock` Regular text content. - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `type BetaManagedAgentsSearchResultBlock` A block containing a web search result. - `Type BetaManagedAgentsSearchResultBlockType` - `Citations BetaManagedAgentsSearchResultCitations` Citation settings for this search result. - `Enabled bool` Whether citations are enabled for this search result. - `Content []BetaManagedAgentsSearchResultContent` Array of text content blocks from the search result. - `Type BetaManagedAgentsSearchResultContentType` - `Text string` The text content. minLength: 1 - `Source string` The URL source of the search result. minLength: 1 - `Title string` The title of the search result. minLength: 1 - `IsError bool Optional` Whether the tool execution resulted in an error. - `ProcessedAt Time Optional` Timestamp when this result was processed. format: date-time - `SessionThreadID string Optional` Set by the server to the subagent thread this result was routed to. Omitted when it was routed to the primary thread. - `type BetaManagedAgentsUserDefineOutcomeEvent` Echo of a `user.define_outcome` input event. Carries the server-generated `outcome_id` that subsequent `span.outcome_evaluation_*` events reference. - `Type BetaManagedAgentsUserDefineOutcomeEventType` - `ID string` Unique identifier for this event. - `Description string` What the agent should produce. Copied from the input event. - `MaxIterations int64` Evaluate-then-revise cycles before giving up. Default 3, max 20. format: int32 - `OutcomeID string` Server-generated `outc_` ID for this outcome. Referenced by `span.outcome_evaluation_*` events and the session's `outcome_evaluations` list. - `ProcessedAt Time` Timestamp when the outcome was accepted. format: date-time - `Rubric BetaManagedAgentsUserDefineOutcomeEventRubricUnion` How to grade the outcome. File rubrics are currently resolved to their text content; clients should handle both variants. - `type BetaManagedAgentsFileRubric` Rubric referenced by a file uploaded via the Files API. - `Type BetaManagedAgentsFileRubricType` - `FileID string` ID of the rubric file. - `type BetaManagedAgentsTextRubric` Rubric content provided inline as text. - `Type BetaManagedAgentsTextRubricType` - `Content string` Rubric content. Plain text or markdown — the grader treats it as freeform text. - `type 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. - `Type BetaManagedAgentsUserToolResultEventType` - `ID string` Unique identifier for this event. - `ToolUseID 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?sdk_languages=go#beta_managed_agents_session_requires_action.event_ids) `stop_reason.event_ids` field. - `Content []BetaManagedAgentsUserToolResultEventContentUnion Optional` The result content returned by the tool. - `type BetaManagedAgentsTextBlock` Regular text content. - `type BetaManagedAgentsImageBlock` Image content specified directly as base64 data or as a reference via a URL. - `type BetaManagedAgentsDocumentBlock` Document content, either specified directly as base64 data, as text, or as a reference via a URL. - `type BetaManagedAgentsSearchResultBlock` A block containing a web search result. - `IsError bool Optional` Whether the tool execution resulted in an error. - `ProcessedAt Time Optional` Timestamp when this result was processed. format: date-time - `SessionThreadID string Optional` Set by the server to the subagent thread this result was routed to. Omitted when it was routed to the primary thread. - `type BetaManagedAgentsSystemMessageEvent` A mid-conversation system message event. Carries system-role content that is appended to the session as a `role: "system"` turn. - `Type BetaManagedAgentsSystemMessageEventType` - `ID string` Unique identifier for this event. - `Content []BetaManagedAgentsSystemContentBlock` System content blocks. Text-only. - `Type BetaManagedAgentsSystemContentBlockType` - `Text string` The text content. minLength: 1 - `ProcessedAt Time Optional` Timestamp when this system message was processed. format: date-time ## Example ```go package main import ( "context" "fmt" "github.com/anthropics/anthropic-sdk-go" "github.com/anthropics/anthropic-sdk-go/option" ) func main() { client := anthropic.NewClient( option.WithAPIKey("my-anthropic-api-key"), ) betaManagedAgentsSendSessionEvents, err := client.Beta.Sessions.Events.Send( context.TODO(), "sesn_011CZkZAtmR3yMPDzynEDxu7", anthropic.BetaSessionEventSendParams{ Events: []anthropic.BetaManagedAgentsEventParamsUnion{anthropic.BetaManagedAgentsEventParamsUnion{ OfUserMessage: &anthropic.BetaManagedAgentsUserMessageEventParams{ Content: []anthropic.BetaManagedAgentsUserMessageEventParamsContentUnion{anthropic.BetaManagedAgentsUserMessageEventParamsContentUnion{ OfText: &anthropic.BetaManagedAgentsTextBlockParam{ Text: "Where is my order #1234?", Type: anthropic.BetaManagedAgentsTextBlockTypeText, }, }}, Type: anthropic.BetaManagedAgentsUserMessageEventParamsTypeUserMessage, }, }}, }, ) if err != nil { panic(err.Error()) } fmt.Printf("%+v\n", betaManagedAgentsSendSessionEvents.Data) } ``` ### 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" } ] } ```