> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hyperspell.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Call an approved tool on an external MCP server

> ``tools/call`` against a connected ``mcp:<label>`` source
(specs/components/external-mcp-source.md). Only tools the app owner
approved — and whose shape still matches what was approved — are callable;
everything else is rejected before any packet reaches the server.



## OpenAPI

````yaml https://app.stainlessapi.com/api/spec/documented/hyperspell.yaml post /live/{source}/tool
openapi: 3.1.0
info:
  title: Hyperspell API
  summary: >-
    Hyperspell is the memory layer for AI apps and agents. Through the API, you
    can add memories, connect data sources to index them in real-time, and
    search memories with our natural language query engine.
  termsOfService: https://hyperspell.com/blog/tos
  contact:
    name: Hyperspell
    url: https://hyperspell.com/
    email: hello@hyperspell.com
  version: 0.32.1
servers:
  - url: https://api.hyperspell.com
    description: Production
security:
  - APIKey: []
    AsUser: []
paths:
  /live/{source}/tool:
    post:
      tags:
        - Live
      summary: Call an approved tool on an external MCP server
      description: >-
        ``tools/call`` against a connected ``mcp:<label>`` source

        (specs/components/external-mcp-source.md). Only tools the app owner

        approved — and whose shape still matches what was approved — are
        callable;

        everything else is rejected before any packet reaches the server.
      operationId: live_source_tool_live__source__tool_post
      parameters:
        - name: source
          in: path
          required: true
          schema:
            type: string
            title: Source
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ToolCallRequest'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ToolCallResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      security:
        - APIKey: []
        - AsUser: []
components:
  schemas:
    ToolCallRequest:
      properties:
        tool:
          type: string
          title: Tool
          description: The approved tool name to call.
        arguments:
          anyOf:
            - additionalProperties: true
              type: object
            - type: 'null'
          title: Arguments
          description: Arguments matching the tool's declared input schema.
      type: object
      required:
        - tool
      title: ToolCallRequest
    ToolCallResponse:
      properties:
        source:
          type: string
          title: Source
        tool:
          type: string
          title: Tool
        payload:
          title: Payload
        truncated:
          type: boolean
          title: Truncated
          default: false
        notes:
          items:
            type: string
          type: array
          title: Notes
        is_error:
          type: boolean
          title: Is Error
          default: false
      type: object
      required:
        - source
        - tool
        - payload
      title: ToolCallResponse
      description: 'One external MCP tool call: the tool''s payload, capped and annotated.'
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    APIKey:
      type: http
      description: >-
        API Key or JWT User Token. If using an API Key, set the X-As-User header
        to act as a specific user. A JWT User Token is always scoped to a
        specific user.
      scheme: bearer
      bearerFormat: Bearer <token>
    AsUser:
      type: apiKey
      description: >-
        Optionally set this header to act as a specific user when using an API
        Key, equivalent to first exchanging the API Key for a User Token
      in: header
      name: X-As-User

````