MCP REST API Tester

A TypeScript-based MCP server that enables testing of REST APIs through Cline. This tool allows you to test and interact with any REST API endpoints directly from your development environment.

Installation

Installing via Smithery

To install REST API Tester for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install dkmaker-mcp-rest-api --client claude

Installing Manually

Install the package globally:

npm install -g dkmaker-mcp-rest-api

Configure Cline Custom Instructions:

To ensure Cline understands how to effectively use this tool, add the following to your Cline custom instructions (Settings > Custom Instructions):

# REST API Testing Instructions

The `test_request` tool enables testing, debugging, and interacting with REST API endpoints. The tool provides comprehensive request/response information and handles authentication automatically.

## When to Use

- Testing specific API endpoints
- Debugging API responses
- Verifying API functionality
- Checking response times
- Validating request/response formats
- Testing local development servers
- Testing API sequences
- Verifying error handling

## Key Features

- Supports GET, POST, PUT, DELETE methods
- Handles authentication (Basic, Bearer, API Key)
- Normalizes endpoints automatically
- Provides detailed response information
- Configurable SSL verification and response limits

## Resources

The following resources provide detailed documentation:

- examples: Usage examples and common patterns
- response-format: Response structure and fields
- config: Configuration options and setup guide

Access these resources to understand usage, response formats, and configuration options.

## Important Notes

- Review API implementation for expected behavior
- Handle sensitive data appropriately
- Consider rate limits and API constraints
- Restart server after configuration changes

Add the server to your MCP configuration:

While these instructions are for Cline, the server should work with any MCP implementation. Configure based on your operating system:

Windows

⚠️ IMPORTANT: Due to a known issue with Windows path resolution (issue #40), you must use the full path instead of %APPDATA%.

Add to C:\Users\<YourUsername>\AppData\Roaming\Code\User\globalStorage\saoudrizwan.claude-dev\settings\cline_mcp_settings.json:

{
  "mcpServers": {
    "rest-api": {
      "command": "node",
      "args": [
        "C:/Users/<YourUsername>/AppData/Roaming/npm/node_modules/dkmaker-mcp-rest-api/build/index.js"
      ],
      "env": {
        "REST_BASE_URL": "https://api.example.com",
        // Basic Auth
        "AUTH_BASIC_USERNAME": "your-username",
        "AUTH_BASIC_PASSWORD": "your-password",
        // OR Bearer Token
        "AUTH_BEARER": "your-token",
        // OR API Key
        "AUTH_APIKEY_HEADER_NAME": "X-API-Key",
        "AUTH_APIKEY_VALUE": "your-api-key",
        // SSL Verification (enabled by default)
        "REST_ENABLE_SSL_VERIFY": "false", // Set to false to disable SSL verification for self-signed certificates
        // Response Size Limit (optional, defaults to 10000 bytes)
        "REST_RESPONSE_SIZE_LIMIT": "10000", // Maximum response size in bytes
        // Custom Headers (optional)
        "HEADER_X-API-Version": "2.0",
        "HEADER_Custom-Client": "my-client",
        "HEADER_Accept": "application/json"
      }
    }
  }
}

macOS

Add to ~/Library/Application Support/Code/User/globalStorage/saoudrizwan.claude-dev/settings/cline_mcp_settings.json:

{
  "mcpServers": {
    "rest-api": {
      "command": "npx",
      "args": [
        "-y",
        "dkmaker-mcp-rest-api"
      ],
      "env": {
        "REST_BASE_URL": "https://api.example.com",
        // Basic Auth
        "AUTH_BASIC_USERNAME": "your-username",
        "AUTH_BASIC_PASSWORD": "your-password",
        // OR Bearer Token
        "AUTH_BEARER": "your-token",
        // OR API Key
        "AUTH_APIKEY_HEADER_NAME": "X-API-Key",
        "AUTH_APIKEY_VALUE": "your-api-key",
        // SSL Verification (enabled by default)
        "REST_ENABLE_SSL_VERIFY": "false", // Set to false to disable SSL verification for self-signed certificates
        // Custom Headers (optional)
        "HEADER_X-API-Version": "2.0",
        "HEADER_Custom-Client": "my-client",
        "HEADER_Accept": "application/json"
      }
    }
  }
}

Note: Replace the environment variables with your actual values. Only configure one authentication method at a time:

Basic Authentication (username/password)
Bearer Token (if Basic Auth is not configured)
API Key (if neither Basic Auth nor Bearer Token is configured)

Features

Test REST API endpoints with different HTTP methods
Support for GET, POST, PUT, and DELETE requests
Detailed response information including status, headers, and body
Custom Headers:
- Global headers via HEADER_* environment variables
- Case-insensitive prefix (HEADER_, header_, HeAdEr_)
- Case preservation for header names
- Priority-based application (per-request > auth > custom)
Request body handling for POST/PUT methods
Response Size Management:
- Automatic response size limiting (default: 10KB/10000 bytes)
- Configurable size limit via REST_RESPONSE_SIZE_LIMIT environment variable
- Clear truncation metadata when responses exceed limit
- Preserves response structure while only truncating body content
SSL Certificate Verification:
- Enabled by default for secure operation
- Can be disabled for self-signed certificates or development environments
- Control via REST_ENABLE_SSL_VERIFY environment variable
Multiple authentication methods:
- Basic Authentication (username/password)
- Bearer Token Authentication
- API Key Authentication (custom header)

Usage Examples

Once installed and configured, you can use the REST API Tester through Cline to test your API endpoints:

// Test a GET endpoint
use_mcp_tool('rest-api', 'test_request', {
  "method": "GET",
  "endpoint": "/users"
});

// Test a POST endpoint with body
use_mcp_tool('rest-api', 'test_request', {
  "method": "POST",
  "endpoint": "/users",
  "body": {
    "name": "John Doe",
    "email": "john@example.com"
  }
});

// Test with custom headers
use_mcp_tool('rest-api', 'test_request', {
  "method": "GET",
  "endpoint": "/products",
  "headers": {
    "Accept-Language": "en-US",
    "X-Custom-Header": "custom-value"
  }
});

Development

Clone the repository:

git clone https://github.com/zenturacp/mcp-rest-api.git
cd mcp-rest-api

Install dependencies:

npm install

Build the project:

npm run build

For development with auto-rebuild:

npm run watch

License

This project is licensed under the MIT License - see the LICENSE file for details.