> ## Documentation Index
> Fetch the complete documentation index at: https://test-8862363a-tembo-update-free-byok-chatgpt-copy.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Session Message

> Create a message for an existing session and queue a follow-up job



## OpenAPI

````yaml /openapi.self-hosted.yml post /session/{sessionId}/messages
openapi: 3.1.0
info:
  title: Self-Hosted Developer API
  description: Tembo Self-Hosted Developer API
  version: 1.0.0
servers:
  - url: https://tembo.example.com/api/public-api/
    description: Tembo self-hosted API
security: []
paths:
  /session/{sessionId}/messages:
    post:
      summary: Send Session Message
      description: Create a message for an existing session and queue a follow-up job
      operationId: postPublic-apiSessionSessionIdMessages
      parameters:
        - name: sessionId
          in: path
          description: ID of the session to continue
          required: true
          schema:
            type: string
            format: uuid
      requestBody:
        description: Session message payload
        content:
          application/json:
            schema:
              type: object
              properties:
                content:
                  type: string
                  minLength: 1
                  description: Follow-up instructions for the session
                jsonContent:
                  type: string
                  description: Structured message content serialized as JSON
                artifactId:
                  type: string
                  format: uuid
                  description: Artifact to associate with the follow-up
                pullRequestId:
                  type: string
                  format: uuid
                  description: Pull request to associate with the follow-up
                mcpServers:
                  type: array
                  items:
                    type: string
                  description: MCP server identifiers available to the agent
                agentOptions:
                  type: object
                  additionalProperties: true
                  description: Agent runtime options for this follow-up
                slashCommand:
                  type: object
                  properties:
                    command:
                      type: string
                      minLength: 1
                    arguments:
                      type: string
                  required:
                    - command
              required:
                - content
        required: true
      responses:
        '200':
          description: Message created successfully
          content:
            application/json:
              schema:
                type: object
                properties:
                  message:
                    type: object
                    properties:
                      id:
                        type: string
                      content:
                        type: string
                      createdAt:
                        type: string
                        format: date-time
                      isQueued:
                        type: boolean
                    required:
                      - id
                      - content
                      - createdAt
                      - isQueued
                  job:
                    anyOf:
                      - type: object
                        properties:
                          id:
                            type: string
                          task:
                            type: string
                        required:
                          - id
                          - task
                      - type: 'null'
                  hotPath:
                    anyOf:
                      - type: object
                        properties:
                          providerSessionId:
                            type: string
                          activeProviderTurnId:
                            type: string
                          queuedTurnId:
                            type: string
                          mode:
                            type: string
                            enum:
                              - started
                              - steered
                              - queued
                          transport:
                            type: string
                      - type: 'null'
                  session:
                    type: object
                    properties:
                      id:
                        type: string
                      title:
                        type: string
                    required:
                      - id
                      - title
                required:
                  - message
                  - job
                  - session
        '400':
          description: Bad request
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                required:
                  - error
        '404':
          description: Session not found
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                required:
                  - error
      x-codeSamples:
        - lang: bash
          label: cURL
          source: |-
            curl -s -X POST \
              "https://api.tembo.io/session/${SESSION_ID}/messages" \
              -H "Authorization: Bearer ${API_KEY}" \
              -H "Content-Type: application/json" \
              -d '{"content": "Please add a regression test for this change."}'

````