OpenAPI

OpenAPI MCP Server lets you expose any OpenAPI v3.1 compliant API as an MCP proxy you can interact with through Claude Desktop. It automatically translates API endpoints, parameters, and responses into Claude tools, so you can discover, call, and work with APIs in a natural conversation.

How to use

You connect Claude Desktop to an OpenAPI MCP Server to work with any OpenAPI v3.1 API as if you were chatting with a capable assistant. The server converts endpoints into Claude-usable tools, letting you browse available operations, see required parameters, and trigger API calls. You can also upload files to endpoints that accept multipart/form-data when supported by the API.

Typical usage patterns include asking questions like: which endpoints exist for a given API, what parameters are required for a specific operation, or to perform an action such as fetching a resource or uploading a file. When an endpoint accepts file uploads, you can provide local file paths and the server will handle reading and sending the files as part of the API request.

How to install

Prerequisites you need installed on your system are Node.js and a package manager. Follow the steps below to install dependencies, build, and run an MCP server that can be used by Claude Desktop.

# Install dependencies for the MCP project
pnpm install

# Run tests to ensure everything is working
pnpm test

# Build the project for production use
pnpm build

# Link the project to your global node_modules so that npx works
npm link

# Now start Claude Desktop to use the MCP server

# After making changes, rebuild before restarting Claude Desktop
pnpm build

# Restart Claude Desktop to run with the latest changes

Configuration

Configure Claude Desktop to load an MCP server by adding the MCP entry in your Claude desktop config. The example shows a Petstore OpenAPI JSON file being served via the MCP server using npx. Adapt the path to your OpenAPI spec as needed.

{
  "mcpServers": {
    "petstore_api": {
      "command": "npx",
      "args": ["openapi-mcp-server", "/abs/path/to/petstore-openapi.json"]
    }
  }
}

Examples

A practical setup uses a Petstore-style OpenAPI document. The MCP server hosts the API proxy locally so Claude can discover endpoints, understand required parameters, and call the API on your behalf. For endpoints that support file uploads, provide local file paths and the server handles streaming the file to the API.

Notes and considerations

This server focuses on OpenAPI v3.1 specifications and is optimized for JSON or plain text responses. File uploads are supported for endpoints that accept multipart/form-data, using local files only. Large files are streamed to the API and progress reporting is available for large uploads.