Braintrust Functions API

openapi: 3.0.3
info:
  title: Braintrust REST ACL Functions API
  description: The Braintrust REST API for building, evaluating, and observing AI applications. The API is organized around REST, uses predictable resource-oriented URLs under https://api.braintrust.dev/v1, accepts and returns JSON, and authenticates with a Bearer API key. This specification covers the core documented resource surface - projects, experiments, datasets, logs/spans, prompts, functions and scorers, evals, project configuration, organization/ACL management, credentials, and the OpenAI-compatible AI proxy.
  termsOfService: https://www.braintrust.dev/legal/terms-of-service
  contact:
    name: Braintrust Support
    email: support@braintrust.dev
    url: https://www.braintrust.dev/docs
  version: '1.0'
servers:
- url: https://api.braintrust.dev
  description: US data plane (default)
- url: https://api-eu.braintrust.dev
  description: EU data plane
security:
- bearerAuth: []
tags:
- name: Functions
paths:
  /v1/function:
    get:
      operationId: getFunction
      tags:
      - Functions
      summary: List functions
      parameters:
      - $ref: '#/components/parameters/Limit'
      - name: project_id
        in: query
        schema:
          type: string
          format: uuid
      - name: function_name
        in: query
        schema:
          type: string
      - name: slug
        in: query
        schema:
          type: string
      responses:
        '200':
          description: Returns a list of functions.
          content:
            application/json:
              schema:
                type: object
                properties:
                  objects:
                    type: array
                    items:
                      $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
    post:
      operationId: postFunction
      tags:
      - Functions
      summary: Create function
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateFunction'
      responses:
        '200':
          description: Returns the new function object.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
    put:
      operationId: putFunction
      tags:
      - Functions
      summary: Create or replace function
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateFunction'
      responses:
        '200':
          description: Returns the function object.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v1/function/{function_id}:
    parameters:
    - name: function_id
      in: path
      required: true
      schema:
        type: string
        format: uuid
    get:
      operationId: getFunctionId
      tags:
      - Functions
      summary: Get function
      responses:
        '200':
          description: Returns the function object.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: patchFunctionId
      tags:
      - Functions
      summary: Partially update function
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                name:
                  type: string
                description:
                  type: string
                function_data:
                  type: object
                  additionalProperties: true
      responses:
        '200':
          description: Returns the updated function object.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
    delete:
      operationId: deleteFunctionId
      tags:
      - Functions
      summary: Delete function
      responses:
        '200':
          description: Returns the deleted function object.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Function'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v1/function/{function_id}/invoke:
    parameters:
    - name: function_id
      in: path
      required: true
      schema:
        type: string
        format: uuid
    post:
      operationId: postFunctionIdInvoke
      tags:
      - Functions
      summary: Invoke function
      description: Invoke a function (a prompt, code, or LLM scorer) server-side with the given input. Optionally stream the result and write a trace span to a parent object.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InvokeFunctionRequest'
      responses:
        '200':
          description: Returns the function result, or an SSE stream when stream is true.
          content:
            application/json:
              schema:
                description: The return value of the function. Shape depends on the function.
            text/event-stream:
              schema:
                type: string
                description: Server-Sent Events stream of the function result when stream is true.
        '401':
          $ref: '#/components/responses/Unauthorized'
components:
  schemas:
    PromptData:
      type: object
      description: The prompt template, model, and parameters.
      properties:
        prompt:
          type: object
          additionalProperties: true
          description: The prompt block - chat messages or a completion template.
        options:
          type: object
          additionalProperties: true
          description: Model and parameter options (model, temperature, max_tokens, etc).
        parser:
          type: object
          nullable: true
          additionalProperties: true
        tool_functions:
          type: array
          nullable: true
          items:
            type: object
            additionalProperties: true
    Function:
      type: object
      properties:
        id:
          type: string
          format: uuid
        project_id:
          type: string
          format: uuid
        name:
          type: string
        slug:
          type: string
        description:
          type: string
          nullable: true
        created:
          type: string
          format: date-time
          nullable: true
        function_type:
          type: string
          nullable: true
          enum:
          - llm
          - scorer
          - task
          - tool
        function_data:
          type: object
          additionalProperties: true
        prompt_data:
          $ref: '#/components/schemas/PromptData'
        function_schema:
          type: object
          nullable: true
          additionalProperties: true
        log_id:
          type: string
          enum:
          - p
    Error:
      type: object
      properties:
        error:
          type: string
          description: A human-readable error message.
    InvokeFunctionRequest:
      type: object
      properties:
        input:
          description: The input to the function. Shape depends on the function.
        messages:
          type: array
          items:
            type: object
            additionalProperties: true
        parent:
          description: Span parent properties; the result of the invocation will be logged as a span under this parent.
          oneOf:
          - type: string
          - type: object
            additionalProperties: true
        stream:
          type: boolean
          description: If true, the response is returned as a Server-Sent Events stream.
        version:
          type: string
          description: The version (transaction id) of the function to invoke.
        mode:
          type: string
          enum:
          - auto
          - parallel
    CreateFunction:
      type: object
      required:
      - project_id
      - name
      - slug
      - function_data
      properties:
        project_id:
          type: string
          format: uuid
        name:
          type: string
        slug:
          type: string
        description:
          type: string
        function_type:
          type: string
          enum:
          - llm
          - scorer
          - task
          - tool
        function_data:
          type: object
          additionalProperties: true
          description: The implementation - a prompt, inline code, a global function, or a reference to existing code.
        prompt_data:
          $ref: '#/components/schemas/PromptData'
        function_schema:
          type: object
          additionalProperties: true
  responses:
    Unauthorized:
      description: Authentication failed - missing or invalid API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The requested resource was not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    Limit:
      name: limit
      in: query
      description: Limit the number of objects to return.
      schema:
        type: integer
        minimum: 0
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API key or JWT
      description: 'Authenticate requests with your Braintrust API key in the Authorization header, e.g. `Authorization: Bearer $BRAINTRUST_API_KEY`.'