Letta Tools API

openapi: 3.0.3
info:
  title: Letta Agent Templates Tools API
  description: The Letta API creates and operates stateful AI agents whose memory - core context blocks and archival vector memory - persists across sessions. It configures the tools, data sources, identities, and multi-agent groups an agent uses, sends and streams messages to agents, and inspects the runs, jobs, and steps behind every agent response. The same OpenAPI-documented interface is served by the managed Letta Cloud API and by the open-source, self-hostable Letta server. All requests require a Bearer API key.
  version: 1.0.0
  contact:
    name: Letta
    url: https://www.letta.com
  license:
    name: Apache-2.0
    url: https://github.com/letta-ai/letta/blob/main/LICENSE
servers:
- url: https://api.letta.com/v1
  description: Letta Cloud
- url: http://localhost:8283/v1
  description: Self-hosted (default local port)
security:
- bearerAuth: []
tags:
- name: Tools
  description: Functions agents can call, including MCP-backed tools.
paths:
  /v1/tools/:
    get:
      tags:
      - Tools
      summary: List Tools
      description: Get a list of all tools available to agents.
      parameters:
      - name: before
        in: query
        required: false
        description: Tool ID cursor for pagination. Returns tools that come before this tool ID in the specified sort order
        schema:
          type: string
      - name: after
        in: query
        required: false
        description: Tool ID cursor for pagination. Returns tools that come after this tool ID in the specified sort order
        schema:
          type: string
      - name: limit
        in: query
        required: false
        description: Maximum number of tools to return
        schema:
          type: string
          default: 50
      - name: order
        in: query
        required: false
        description: Sort order for tools by creation time. 'asc' for oldest first, 'desc' for newest first
        schema:
          type: string
          default: desc
          enum:
          - asc
          - desc
      - name: order_by
        in: query
        required: false
        description: Field to sort by
        schema:
          type: string
          default: created_at
      - name: name
        in: query
        required: false
        description: Filter by single tool name
        schema:
          type: string
      - name: names
        in: query
        required: false
        description: Filter by specific tool names
        schema:
          type: string
      - name: tool_ids
        in: query
        required: false
        description: Filter by specific tool IDs - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: search
        in: query
        required: false
        description: Search tool names (case-insensitive partial match)
        schema:
          type: string
      - name: tool_types
        in: query
        required: false
        description: Filter by tool type(s) - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: exclude_tool_types
        in: query
        required: false
        description: Tool type(s) to exclude - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: return_only_letta_tools
        in: query
        required: false
        description: Return only tools with tool_type starting with 'letta_'
        schema:
          type: string
          default: false
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/Tool'
        '401':
          $ref: '#/components/responses/Unauthorized'
    post:
      tags:
      - Tools
      summary: Create Tool
      description: Create a new tool
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateToolRequest'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Tool'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
    put:
      tags:
      - Tools
      summary: Upsert Tool
      description: Create or update a tool
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/count:
    get:
      tags:
      - Tools
      summary: Count Tools
      description: Get a count of all tools available to agents belonging to the org of the user.
      parameters:
      - name: name
        in: query
        required: false
        schema:
          type: string
      - name: names
        in: query
        required: false
        description: Filter by specific tool names
        schema:
          type: string
      - name: tool_ids
        in: query
        required: false
        description: Filter by specific tool IDs - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: search
        in: query
        required: false
        description: Search tool names (case-insensitive partial match)
        schema:
          type: string
      - name: tool_types
        in: query
        required: false
        description: Filter by tool type(s) - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: exclude_tool_types
        in: query
        required: false
        description: Tool type(s) to exclude - accepts repeated params or comma-separated values
        schema:
          type: string
      - name: return_only_letta_tools
        in: query
        required: false
        description: Count only tools with tool_type starting with 'letta_'
        schema:
          type: string
          default: false
      - name: exclude_letta_tools
        in: query
        required: false
        description: Exclude built-in Letta tools from the count
        schema:
          type: string
          default: false
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v1/tools/add-base-tools:
    post:
      tags:
      - Tools
      summary: Upsert Base Tools
      description: Upsert base tools
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/run:
    post:
      tags:
      - Tools
      summary: Run Tool From Source
      description: Attempt to build a tool from source, then run it on the provided arguments
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/search:
    post:
      tags:
      - Tools
      summary: Search Tools
      description: Search tools using semantic search.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/{tool_id}:
    delete:
      tags:
      - Tools
      summary: Delete Tool
      description: Delete a tool by name
      parameters:
      - name: tool_id
        in: path
        required: true
        description: The ID of the tool in the format 'tool-<uuid4>'
        schema:
          type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
    get:
      tags:
      - Tools
      summary: Retrieve Tool
      description: Get a tool by ID
      parameters:
      - name: tool_id
        in: path
        required: true
        description: The ID of the tool in the format 'tool-<uuid4>'
        schema:
          type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Tool'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      tags:
      - Tools
      summary: Modify Tool
      description: Update an existing tool
      parameters:
      - name: tool_id
        in: path
        required: true
        description: The ID of the tool in the format 'tool-<uuid4>'
        schema:
          type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateToolRequest'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Tool'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/mcp/servers:
    get:
      tags:
      - Tools
      summary: List Mcp Servers
      description: Get a list of all configured MCP servers
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/McpServerConfig'
        '401':
          $ref: '#/components/responses/Unauthorized'
    put:
      tags:
      - Tools
      summary: Add Mcp Server To Config
      description: Add a new MCP server to the Letta MCP server config
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/mcp/servers/connect:
    post:
      tags:
      - Tools
      summary: Connect Mcp Server
      description: 'Connect to an MCP server with support for OAuth via SSE.

        Returns a stream of events handling authorization state and exchange if OAuth is required.'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
            text/event-stream:
              description: Server-Sent Events stream
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/mcp/servers/test:
    post:
      tags:
      - Tools
      summary: Test Mcp Server
      description: 'Test connection to an MCP server without adding it.

        Returns the list of available tools if successful.'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/mcp/servers/{mcp_server_name}:
    patch:
      tags:
      - Tools
      summary: Update Mcp Server
      description: Update an existing MCP server configuration
      parameters:
      - name: mcp_server_name
        in: path
        required: true
        schema:
          type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
    delete:
      tags:
      - Tools
      summary: Delete Mcp Server From Config
      description: Delete a MCP server configuration
      parameters:
      - name: mcp_server_name
        in: path
        required: true
        schema:
          type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /v1/tools/mcp/servers/{mcp_server_name}/resync:
    post:
      tags:
      - Tools
      summary: Resync Mcp Server Tools
      description: 'Resync tools for an MCP server by:

        1. Fetching current tools from the MCP server

        2. Deleting tools that no longer exist on the server

        3. Updating schemas for existing tools

        4. Adding new tools from the server'
      parameters:
      - name: mcp_server_name
        in: path
        required: true
        schema:
          type: string
      - name: agent_id
        in: query
        required: false
        schema:
          type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/tools/mcp/servers/{mcp_server_name}/tools:
    get:
      tags:
      - Tools
      summary: List Mcp Tools By Server
      description: Get a list of all tools for a specific MCP server
      parameters:
      - name: mcp_server_name
        in: path
        required: true
        schema:
          type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /v1/tools/mcp/servers/{mcp_server_name}/tools/{tool_name}/execute:
    post:
      tags:
      - Tools
      summary: Execute Mcp Tool
      description: 'Execute a specific MCP tool from a configured server.

        Returns the tool execution result.'
      parameters:
      - name: mcp_server_name
        in: path
        required: true
        schema:
          type: string
      - name: tool_name
        in: path
        required: true
        schema:
          type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    CreateToolRequest:
      type: object
      required:
      - source_code
      properties:
        source_code:
          type: string
        description:
          type: string
        tags:
          type: array
          items:
            type: string
        source_type:
          type: string
          default: python
        json_schema:
          type: object
          additionalProperties: true
    Tool:
      type: object
      description: A function an agent can call.
      properties:
        id:
          type: string
        name:
          type: string
        tool_type:
          type: string
        description:
          type: string
        source_type:
          type: string
          example: python
        source_code:
          type: string
        json_schema:
          type: object
          additionalProperties: true
        args_json_schema:
          type: object
          additionalProperties: true
        tags:
          type: array
          items:
            type: string
        pip_requirements:
          type: array
          items:
            type: object
            additionalProperties: true
        default_requires_approval:
          type: boolean
    HTTPValidationError:
      type: object
      properties:
        detail:
          type: array
          items:
            type: object
            properties:
              loc:
                type: array
                items:
                  type: string
              msg:
                type: string
              type:
                type: string
    McpServerConfig:
      type: object
      description: A configured remote MCP (Model Context Protocol) tool server. Shape varies by transport (stdio, SSE, or Streamable HTTP).
      properties:
        id:
          type: string
        server_name:
          type: string
        type:
          type: string
          enum:
          - sse
          - stdio
          - streamable_http
        server_url:
          type: string
          format: uri
        command:
          type: string
        args:
          type: array
          items:
            type: string
        env:
          type: object
          additionalProperties:
            type: string
        custom_headers:
          type: object
          additionalProperties:
            type: string
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            message:
              type: string
            code:
              type: string
  responses:
    Unauthorized:
      description: Missing or invalid Bearer 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'
    ValidationError:
      description: The request payload failed validation.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/HTTPValidationError'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'API key created at https://app.letta.com/api-keys, passed as `Authorization: Bearer YOUR_API_KEY`.'