MCP Swagger Server

An MCP (Model Context Protocol) server that automatically converts REST APIs with Swagger/OpenAPI documentation into MCP tools, making them accessible to MCP-compatible clients.

Features

• 🔄 Automatic Tool Generation: Converts Swagger/OpenAPI endpoints to MCP tools
• 🔒 SSL Certificate Handling: Option to ignore SSL certificate errors for internal APIs
• 🏷️ Custom Tool Prefixes: Organize tools with custom prefixes for better organization
• 📡 Stdio Transport: Uses stdio format as the default transport mechanism
• 🌐 Flexible Input: Supports both URL and local file swagger documentation
• 🔧 Parameter Support: Handles path, query, and body parameters
• 📝 Type Mapping: Maps Swagger types to JSON Schema types for proper validation

Installation

Global Installation

npm install -g mcp-swagger

From Source

git clone https://github.com/HainanZhao/mcp-swagger.git
cd mcp-swagger
npm install
npm run build

Usage

Command Line Options

mcp-swagger [options]

Options:
  -u, --swagger-url <url>      URL to swagger documentation
  -f, --swagger-file <file>    Path to local swagger file
  -p, --tool-prefix <prefix>   Custom prefix for generated tools
  -b, --base-url <url>         Override base URL for API calls
  --ignore-ssl                 Ignore SSL certificate errors
  -a, --auth-header <header>   Authentication header (e.g., "Bearer token")
  -h, --help                   Display help information
  -V, --version                Display version number

Examples

Load from URL with custom prefix

mcp-swagger --swagger-url https://api.example.com/swagger.json --tool-prefix example --ignore-ssl

Load from local file

mcp-swagger --swagger-file ./api-docs.json --tool-prefix local-api

With authentication

mcp-swagger --swagger-url https://api.example.com/swagger.json --auth-header "Bearer your-token-here"

Override base URL

mcp-swagger --swagger-file ./swagger.json --base-url https://staging.api.com --tool-prefix staging

Configuration

The server can be configured through command-line arguments or environment variables:

CLI Option	Environment Variable	Description
--swagger-url	SWAGGER_URL	URL to swagger documentation
--swagger-file	SWAGGER_FILE	Path to local swagger file
--tool-prefix	TOOL_PREFIX	Custom prefix for generated tools
--base-url	BASE_URL	Override base URL for API calls
--ignore-ssl	IGNORE_SSL=true	Ignore SSL certificate errors
--auth-header	AUTH_HEADER	Authentication header

MCP Integration

Add to your Agent configuration (e.g. claude_desktop_config.json or ~/.gemini/settings.json):

{
  "mcpServers": {
    "swagger-api": {
      "command": "mcp-swagger",
      "args": [
        "--swagger-url", "https://example.com/swagger.json",
        "--tool-prefix", "example",
        "--ignore-ssl"
      ]
    }
  }
}

Other MCP Clients

The server uses the standard MCP stdio transport, so it should work with any MCP-compatible client. Start the server and connect via stdin/stdout.

Generated Tools

Tool Naming Convention

Tools are named using the following pattern:

• {prefix}_{method}_{path_segments}
• Path parameters are converted to by_{parameter_name}

Examples:

• GET /v1/users/ → myapi_get_v1_users
• GET /v1/users/{id} → myapi_get_v1_users_by_id
• POST /v1/users/ → myapi_post_v1_users

Parameter Mapping

• Path parameters: Included in the URL path
• Query parameters: Added as URL query string
• Body parameters: Sent as JSON request body
• Header parameters: Added to request headers

Type Mapping

Swagger Type	JSON Schema Type
string	string
integer	number
boolean	boolean
array	array
object	object

Sample Swagger Document

The server has been tested with the following sample swagger document structure:

{
  "swagger": "2.0",
  "info": {
    "title": "API Documentation",
    "version": "1.0"
  },
  "host": "api.example.com",
  "basePath": "/api",
  "paths": {
    "/v1/hosts/": {
      "get": {
        "summary": "Get a list of hosts",
        "parameters": [
          {
            "name": "filter_by",
            "in": "query",
            "type": "string",
            "description": "Filter criteria"
          }
        ]
      }
    },
    "/v1/hosts/{name}": {
      "get": {
        "summary": "Get host by name",
        "parameters": [
          {
            "name": "name",
            "in": "path",
            "required": true,
            "type": "string"
          }
        ]
      }
    }
  }
}

This would generate tools like:

• example_get_v1_hosts - List hosts with optional filtering
• example_get_v1_hosts_by_name - Get specific host by name

Error Handling

The server includes comprehensive error handling:

• SSL Certificate Errors: Can be ignored with --ignore-ssl flag
• Network Errors: Returned as error responses with details
• Invalid Swagger: Validation errors are reported during startup
• Missing Parameters: Parameter validation based on swagger schema
• HTTP Errors: API response errors are captured and returned

Development

Building

npm run build

Testing

# Test with sample swagger file
npm run test

Linting

npm run lint

Troubleshooting

Common Issues

1. SSL Certificate Errors

   • Use --ignore-ssl flag for internal APIs with self-signed certificates

2. Tool Name Conflicts

   • Use --tool-prefix to add unique prefixes to avoid naming conflicts

3. Base URL Issues

   • Use --base-url to override the base URL from swagger documentation

4. Authentication Failures

   • Provide proper authentication header with --auth-header

Debug Mode

The server logs important information to stderr:

• Swagger document loading status
• Number of tools generated
• Tool generation details

License

MIT License - see LICENSE file for details.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

Support

For issues and questions:

• Create an issue on GitHub
• Check the troubleshooting section above
• Review the sample configurations