> ## Documentation Index > Fetch the complete documentation index at: https://docs.stewrd.dev/llms.txt > Use this file to discover all available pages before exploring further. # Send Session Message > Send a message within a persistent session. The agent receives full conversation history. ## OpenAPI ````yaml POST /v1/sessions/{session_id}/messages openapi: 3.1.0 info: title: Stewrd API description: >- Managed AI agent infrastructure. Bring your own LLM key, send a message, get finished work back. version: 1.0.0 contact: name: Stewrd Support email: team@stewrd.dev url: https://stewrd.dev servers: - url: https://api.stewrd.dev description: Production security: - bearerAuth: [] paths: /v1/sessions/{session_id}/messages: post: tags: - Sessions summary: Send a session message description: >- Send a message within a persistent session. The agent receives the full conversation history automatically. operationId: sendSessionMessage parameters: - name: session_id in: path required: true schema: type: string format: uuid description: The session ID returned from Create Session. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AgentRequest' examples: simple: summary: Send a message value: message: Research the top 5 project management tools follow-up: summary: Follow-up message value: message: Create a comparison table of those tools as a CSV responses: '200': description: Successful session message response content: application/json: schema: $ref: '#/components/schemas/SessionMessageResponse' text/event-stream: schema: type: string description: Server-Sent Events stream. Same events as the agent endpoint. '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Session not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '410': description: Session expired content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: session_expired message: Session expired due to inactivity. '429': description: Quota exceeded content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '502': description: Compute service error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: AgentRequest: type: object required: - message properties: message: type: string description: The task or question for the agent. example: What is the capital of France? capabilities: type: array items: type: string enum: - chat - research - documents - code - data - files description: >- Filter which capabilities to use for this request. Omit to use all capabilities enabled on the project. files: type: array items: $ref: '#/components/schemas/InputFile' description: Files to include with the request. stream: type: boolean default: false description: >- Set to `true` to receive a Server-Sent Events stream instead of a JSON response. Not supported when `tools` is provided. tools: type: array items: $ref: '#/components/schemas/ToolDefinition' description: >- Custom tool definitions for function calling. When provided, only the `chat` capability is used and streaming is disabled. Max 20 tools per request. maxItems: 20 SessionMessageResponse: type: object properties: id: type: string format: uuid description: Unique request identifier. object: type: string enum: - session.message description: Object type, always `session.message`. session_id: type: string format: uuid description: The session this message belongs to. message: type: string description: The agent's response message. capabilities_used: type: array items: type: string description: Capabilities used for this request. files: type: array items: $ref: '#/components/schemas/ResponseFile' description: Files generated by the agent. usage: $ref: '#/components/schemas/Usage' meta: $ref: '#/components/schemas/Meta' ErrorResponse: type: object properties: error: type: object properties: code: type: string description: Machine-readable error code. message: type: string description: Human-readable error description. docs: type: string format: uri description: Link to relevant documentation. InputFile: type: object required: - name - content properties: name: type: string description: File name with extension. example: data.csv content: type: string description: File contents as a string. example: |- id,name,date 1,Alice,2024-01-15 ToolDefinition: type: object required: - name - description - parameters properties: name: type: string pattern: ^[a-zA-Z0-9_]+$ maxLength: 64 description: Tool name — alphanumeric and underscores only. description: type: string maxLength: 1024 description: Description of what the tool does. parameters: type: object description: 'JSON Schema for the tool''s parameters. Must have `type: "object"`.' ResponseFile: type: object properties: name: type: string description: File name. content: type: string description: File contents as a string. url: type: string format: uri description: Download URL for the generated file (when available). Usage: type: object properties: credits_this_request: type: integer description: Credits consumed for this request. 0 on tool output continuations. credits_remaining: type: integer description: Credits remaining in this billing period. tokens_used: type: integer description: Tokens consumed for this request. Meta: type: object properties: duration_ms: type: integer description: Request processing time in milliseconds. project_id: type: string description: The project this request was made against. plan: type: string description: Your current plan. securitySchemes: bearerAuth: type: http scheme: bearer description: >- API key in the format `sk-stw_...`. Get yours at [stewrd.dev/dashboard](https://stewrd.dev/dashboard). ````