API Docs MCP

MCP server for API documentation, supporting GraphQL, OpenAPI/Swagger, and gRPC from local files or remote URLs

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API Docs MCP

Model Context Protocol (MCP) server that provides tools for interacting with API documentation. Supports GraphQL, OpenAPI/Swagger, and gRPC specifications, fetching schema definitions from various sources (local files or remote URLs), caching them, and exposing them through a set of tools.

Table of Contents

MCP Platforms

mcp.so

Features

  • Dynamic Tool Registration: Automatically discovers and registers tools from a specified directory.
  • API Documentation Retrieval: Provides tools to list available API methods (api_docs) and retrieve detailed documentation for specific methods (api_search).
  • Schema Caching: Caches API schema information to reduce redundant fetches and improve performance.
  • Multiple Source Support:
    • GraphQL: Supports loading GraphQL schemas from graphql / gql files or json introspection results (local files or remote URLs).
    • OpenAPI/Swagger: Supports loading OpenAPI/Swagger yaml / yml / json schemas from local files or remote URLs.
    • gRPC: Supports loading gRPC schemas from proto files or via gRPC reflection from remote URLs.
  • Environment-based Configuration: Configures API sources via the API_SOURCES environment variable, allowing flexible deployment and management.
  • Automatic Cache Refresh: Periodically refreshes cached schema data to ensure up-to-date documentation.

Example Use Cases

OpenAPI Petstore retrieval docs

GraphQL retrieval docs

Multiple Sources retrieval docs

Architecture

The api-docs-mcp project is designed as an MCP server that integrates with various API documentation sources.

graph TD
    mcpServer[MCP Server] e1@--> tools(Tools:<br/>api_docs / api_search);
    tools e2@--> cacheManager{Cache Manager};
    cacheManager e3@--> configuration[Configuration:<br/>API_SOURCES env var];
    configuration e4@--> schemaSources{Schema Sources};
    schemaSources e5@-- FileSource--> localFiles(Local Files:<br/>.graphql, .json, .yaml, .proto);
    schemaSources e6@-- UrlSource--> remoteUrls(Remote URLs:<br/>GraphQL Endpoints, OpenAPI/Swagger Endpoints, gRPC Endpoints);
    localFiles e7@--> processor[Schema Processors];
    remoteUrls e8@--> processor;
    processor e9@--> cacheManager;
    processor e10@--> openAPIProcessor(OpenAPI Processor:<br/>OpenAPI/Swagger);
    processor e11@--> graphQLProcessor(GraphQL Processor);
    processor e12@--> grpcProcessor(gRPC Processor)
    cacheManager e13@--Cached Data--> tools;

    subgraph Core Components
        mcpServer
        tools
        cacheManager
        configuration
    end

    subgraph Data Flow
        schemaSources
        localFiles
        remoteUrls
        processor
        openAPIProcessor
        graphQLProcessor
        grpcProcessor
    end

    e1@{ animate: true }
    e2@{ animate: true }
    e3@{ animate: true }
    e4@{ animate: true }
    e5@{ animate: true }
    e6@{ animate: true }
    e7@{ animate: true }
    e8@{ animate: true }
    e9@{ animate: true }
    e10@{ animate: true }
    e11@{ animate: true }
    e12@{ animate: true }
    e13@{ animate: true }

Flow of Operations:

  1. Server Initialization: The index.ts entry point initializes the MCP server and dynamically registers tools defined in the src/tools directory.
  2. Configuration Loading: The CacheManager loads API source configurations from the API_SOURCES environment variable via src/utils/config.ts.
  3. Schema Fetching & Caching:
    • Based on the configured sources (file-based or URL-based), the CacheManager fetches API schemas.
    • For file sources, it reads local files (graphql, gql, json, yaml, yml, proto).
    • For URL sources, it makes HTTP requests to GraphQL, OpenAPI, or gRPC endpoints.
    • Schemas are then processed by specialized handlers (src/api/api.ts for OpenAPI, src/gql/gql.ts for GraphQL, src/grpc/grpc.ts for gRPC).
    • The processed documentation is stored in an in-memory cache (src/utils/cache.ts) with a specified TTL (Time-To-Live).
    • The cache is periodically refreshed.
  4. Tool Usage:
    • api_docs: When invoked, this tool retrieves a list of all available API resources from the cache, filtered by source if provided.
    • api_search: When invoked with a detailName, this tool provides detailed documentation (request, response, error structures) for a specific API resource from the cache.

Installation

To set up the api-docs-mcp server, follow these steps:

  1. Clone the repository:

    git clone https://github.com/EliFuzz/api-docs-mcp.git
cd api-docs-mcp

  2. Install dependencies:

    pnpm install

  3. Build the project:

    pnpm build

Configuration

The server's behavior is controlled by the API_SOURCES environment variable. This variable should contain a JSON string representing an array of SchemaSource objects. Each SchemaSource can be either a FileSource or a UrlSource.

FileSource Example

For a local GraphQL schema:

{
  "name": "MyGraphQLFile",
  "path": "/path/to/your/schema.graphql",
  "type": "gql"
}

For a local OpenAPI JSON schema:

{
  "name": "MyOpenAPIFile",
  "path": "/path/to/your/openapi.json",
  "type": "api"
}

For a local gRPC proto file:

{
  "name": "MyGrpcFile",
  "path": "/path/to/your/service.proto",
  "type": "grpc"
}

UrlSource Example

For a remote GraphQL endpoint:

{
  "name": "GitHubGraphQL",
  "method": "POST",
  "url": "https://api.github.com/graphql",
  "headers": {
    "Authorization": "Bearer YOUR_GITHUB_TOKEN"
  },
  "type": "gql"
}

For a remote OpenAPI endpoint:

{
  "name": "PetstoreAPI",
  "method": "GET",
  "url": "https://petstore.swagger.io/v2/swagger.json",
  "type": "api"
}

For a remote gRPC endpoint with reflection:

{
  "name": "MyGrpcService",
  "url": "grpc://localhost:9090",
  "type": "grpc"
}

Setting the API_SOURCES Environment Variable

You can set this in your shell before running the server:

export API_SOURCES='[{"name": "MyGraphQLFile", "path": "./example/fixtures/graphql/graphql-schema.graphql", "type": "gql"}, {"name": "PetstoreAPI", "method": "GET", "url": "https://petstore.swagger.io/v2/swagger.json", "type": "api"}]'

Or in mcp.json for MCP execution:

"api-docs-mcp": {
    "type": "stdio",
    "command": "npx",
    "args": [ "api-docs-mcp" ],
    "env": {
        "API_SOURCES": "[{\"name\": \"MyGraphQLFile\", \"path\": \"./example/fixtures/graphql/graphql-schema.graphql\", \"type\": \"gql\"}, {\"name\": \"PetstoreAPI\", \"method\": \"GET\", \"url\": \"https://petstore.swagger.io/v2/swagger.json\", \"type\": \"api\"}]"
    }
}

Usage

Once configured and running, the api-docs-mcp server exposes two primary tools: api_docs and api_search.

API Docs Tool

This tool provides a list of all available API methods from the configured sources.

Name: api_docs Description: Get a list of all available API methods. Input Schema:

{
    sourceName?: string; // The name of the API source (e.g., "GitHub") from MCP configuration environment variables. If not provided, docs from all sources will be returned.
}

Output Schema:

{
  sources: Array<{
    sourceName: string; // The name of the source API
    resources: Array<{
      resourceName: string; // The name of the API resource
      resourceType: string; // The type of the API resource (e.g., "POST", "GET", "mutation", "query")
      resourceDescription: string; // A brief description of the API resource
    }>;
  }>;
}

Output Example:

{
  "sources": [
    {
      "sourceName": "GitHubGraphQL",
      "resources": [
        {
          "resourceName": "getUser",
          "resourceType": "query",
          "resourceDescription": "Fetch a user by username"
        },
        {
          "resourceName": "createIssue",
          "resourceType": "mutation",
          "resourceDescription": "Create a new issue in a repository"
        }
      ]
    },
    {
      "sourceName": "PetstoreAPI",
      "resources": [
        {
          "resourceName": "getPetById",
          "resourceType": "GET",
          "resourceDescription": "Find pet by ID"
        },
        {
          "resourceName": "addPet",
          "resourceType": "POST",
          "resourceDescription": "Add a new pet to the store"
        }
      ]
    }
  ]
}

API Search Tool

This tool provides detailed documentation for a specific API method.

Name: api_search Description: Search for a specific API method by name and get its full definition. Input Schema:

{
  resourceName: string; // The exact resource name of the API method to search for that was provided in `api_docs` tool's output
}

Output Schema:

{
  details: Array<{
    sourceName: string; // The name of the source API
    resources: Array<{
      resourceName: string; // The name of the resource
      resourceType: "query" | "mutation" | "subscription"; // The type of GraphQL resource
      resourceDescription: string; // Context or description of the resource
      details: {
        request?: string; // The request structure or input parameters for the API method
        response?: string; // The response structure or output format for the API method
        error?: string; // Error information or error handling details for the API method
      };
    }>;
  }>;
}

Output Example:

{
  "details": [
    {
      "sourceName": "GitHubGraphQL",
      "resources": [
        {
          "resourceName": "getUser",
          "resourceType": "query",
          "resourceDescription": "Fetch a user by username",
          "details": {
            "request": "{ username: String! }",
            "response": "{ id: ID!, login: String!, name: String }",
            "error": "{ message: String!, code: Int! }"
          }
        }
      ]
    }
  ]
}

Development

Running the Server Locally

  1. Set the API_SOURCES environment variable as described in the Configuration section.

  2. Start the server:

    pnpm start

The server will connect to a StdioServerTransport, meaning it will communicate over standard input/output.

Project Structure

.
├── src/
│ ├── api/ # OpenAPI/Swagger schema processing
│ │ └── api.ts
│ ├── gql/ # GraphQL schema processing
│ │ └── gql.ts
│ ├── grpc/ # gRPC schema processing
│ │ └── grpc.ts
│ ├── tools/ # MCP tools definitions
│ │ ├── api_docs.ts
│ │ └── api_search.ts
│ ├── utils/ # Utility functions (cache, config, fetch, file, source)
│ │ ├── cache.ts
│ │ ├── config.ts
│ │ ├── fetch.ts
│ │ ├── file.ts
│ │ └── source.ts
│ ├── index.ts # Main entry point
│ └── server.ts # MCP server setup and tool registration
└── package.json # Project dependencies and scripts
└── README.md # This file

Contributing

Contributions are welcome! Please feel free to open issues or submit pull requests.

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.

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