OpenAPI Proxy MCP server

The OpenAPI MCP Server enables searching and exploring OpenAPI specifications through oapis.org for Claude and Cursor AI assistants. It works by identifying the OpenAPI specification you need, requesting a simple language summary, and determining which endpoints you need with detailed explanations of how they work.

Features

• Get an overview of any OpenAPI specification
• Retrieve details about specific API operations
• Support for both JSON and YAML formats
• Tested with Claude Desktop and Cursor

Installation

Installing via Smithery

The easiest way to install the OpenAPI MCP Server is through Smithery:

npx -y @smithery/cli install @janwilmake/openapi-mcp-server --client claude

You can find client-specific installation instructions on the Smithery page.

Installing using stdio

If you prefer to install manually, you can configure the MCP server in your client's configuration:

{
  "mcpServers": {
    "openapi-mcp-server": {
      "command": "node",
      "args": ["/absolute/path/to/openapi-mcp-server/index.js"],
      "env": {
        "DEBUG": "true"
      }
    }
  }
}

Usage with Claude

After installation, you can use natural language to query API specifications through Claude. For example:

• "Find information about the Stripe API"
• "Explain how to use the GitHub API's repository endpoints"

How It Works

When you ask Claude about an API, the MCP server will:

1. Identify the correct OpenAPI specification
2. Generate a summary of the API in simple language
3. Retrieve specific operation details as needed for your query

Requirements

• Node.js >= 16.17.0
• Claude Desktop, Cursor, or any other MCP client

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "openapi-mcp-server" '{"command":"npx","args":["openapi-mcp-server@latest"]}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "openapi-mcp-server": {
            "command": "npx",
            "args": [
                "openapi-mcp-server@latest"
            ]
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "openapi-mcp-server": {
            "command": "npx",
            "args": [
                "openapi-mcp-server@latest"
            ]
        }
    }
}

3. Restart Claude Desktop for the changes to take effect