MCP Server for Curl

A Model Context Protocol (MCP) server that provides curl functionality, allowing AI assistants to make HTTP requests directly from their environment.

Features

• HTTP Methods: Support for GET, POST, PUT, DELETE requests

• File Downloads: Download files with curl

• Advanced Options: Custom headers, timeouts, redirects, and more

• JSON Support: Built-in JSON data handling for POST/PUT requests

• User Agent: Custom User-Agent string support

• Security: Safe subprocess execution with input validation

Related MCP server: MCP HTTP Client Server

Installation

Method 1: NPM Installation (Recommended)

# Install globally
npm install -g @247arjun/mcp-curl

# Or install locally in your project
npm install @247arjun/mcp-curl

Method 2: From Source

# Clone the repository
git clone https://github.com/247arjun/mcp-curl.git
cd mcp-curl

# Install dependencies
npm install

# Build the project
npm run build

# Optional: Link globally
npm link

Method 3: Direct from GitHub

# Install directly from GitHub
npm install -g git+https://github.com/247arjun/mcp-curl.git

Configuration

Claude Desktop Setup

Add to your Claude Desktop configuration file:

Location:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%/Claude/claude_desktop_config.json

Configuration:

{
  "mcpServers": {
    "mcp-curl": {
      "command": "mcp-curl",
      "args": []
    }
  }
}

Alternative: Using npx (no global install needed)

{
  "mcpServers": {
    "mcp-curl": {
      "command": "npx",
      "args": ["@247arjun/mcp-curl"]
    }
  }
}

Local Development Setup

{
  "mcpServers": {
    "mcp-curl": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-curl/build/index.js"]
    }
  }
}

After adding the configuration, restart Claude Desktop to load the MCP server.

Available Tools

1. curl_get

Make HTTP GET requests.

Parameters:

• url (string): The URL to make the GET request to

• headers (array, optional): HTTP headers in the format 'Header: Value'

• timeout (number, optional): Request timeout in seconds

• follow_redirects (boolean, optional): Whether to follow redirects

• user_agent (string, optional): Custom User-Agent string

Example:

{
  "url": "https://api.example.com/data",
  "headers": ["Authorization: Bearer token"],
  "timeout": 30,
  "follow_redirects": true,
  "user_agent": "MyApp/1.0"
}

2. curl_post

Make HTTP POST requests with data.

Parameters:

• url (string): The URL to make the POST request to

• json_data (object, optional): JSON object to send as POST data

• data (string, optional): Data to send in the POST request body

• headers (array, optional): HTTP headers

• content_type (string, optional): Content-Type header

• timeout (number, optional): Request timeout in seconds

• follow_redirects (boolean, optional): Whether to follow redirects

Example:

{
  "url": "https://api.example.com/data",
  "json_data": {"key": "value"},
  "headers": ["Content-Type: application/json"]
}

3. curl_put

Make HTTP PUT requests.

Parameters:

• url (string): The URL to make the PUT request to

• json_data (object, optional): JSON object to send as PUT data

• data (string, optional): Data to send in the PUT request body

• headers (array, optional): HTTP headers

• content_type (string, optional): Content-Type header

• timeout (number, optional): Request timeout in seconds

• follow_redirects (boolean, optional): Whether to follow redirects

Example:

{
  "url": "https://api.example.com/data/123",
  "data": "raw data",
  "content_type": "text/plain"
}

4. curl_delete

Make HTTP DELETE requests.

Parameters:

• url (string): The URL to make the DELETE request to

• headers (array, optional): HTTP headers

• timeout (number, optional): Request timeout in seconds

• follow_redirects (boolean, optional): Whether to follow redirects

Example:

{
  "url": "https://api.example.com/data/123",
  "headers": ["Authorization: Bearer token"]
}

5. curl_download

Download files.

Parameters:

• url (string): The URL of the file to download

• output_filename (string, optional): Output filename

• resume (boolean, optional): Resume partial download if file exists

• timeout (number, optional): Request timeout in seconds

• follow_redirects (boolean, optional): Whether to follow redirects

Example:

{
  "url": "https://example.com/file.zip",
  "output_filename": "downloaded_file.zip",
  "resume": true
}

6. curl_advanced

Execute curl with custom arguments (advanced users).

Parameters:

• args (array): Array of curl arguments (excluding 'curl' itself)

Example:

{
  "args": ["-X", "PATCH", "-H", "Content-Type: application/json", "-d", "{\"status\":\"updated\"}", "https://api.example.com/items/1"]
}

Usage Examples

Make a GET request

{
  "tool": "curl_get",
  "url": "https://api.example.com/users",
  "headers": ["Authorization: Bearer your-token"]
}

POST JSON data

{
  "tool": "curl_post",
  "url": "https://api.example.com/users",
  "json_data": {
    "name": "John Doe",
    "email": "john@example.com"
  }
}

Download a file

{
  "tool": "curl_download",
  "url": "https://example.com/file.zip",
  "output_filename": "download.zip"
}

Development

Prerequisites

• Node.js 18.0.0 or higher

• npm package manager

• curl command-line tool

Building

npm run build

Testing

Test the server manually:

echo '{"jsonrpc": "2.0", "id": 1, "method": "tools/list", "params": {}}' | node build/index.js

Run tests:

npm test

Linting

npm run lint
npm run lint:fix

Project Structure

mcp-curl/
├── src/
│   └── index.ts          # Main server implementation
├── build/
│   └── index.js          # Compiled JavaScript
├── test/
│   └── basic.test.js     # Basic functionality tests
├── examples/
│   └── test-server.js    # Example usage
├── .github/
│   └── workflows/
│       └── ci.yml        # CI/CD pipeline
├── package.json          # Project configuration
├── tsconfig.json         # TypeScript configuration
├── .eslintrc.json        # ESLint configuration
├── LICENSE               # MIT License
├── DEPLOYMENT.md         # Deployment guide
├── CONTRIBUTING.md       # Contribution guidelines
├── CHANGELOG.md          # Version history
└── README.md             # This file

Verification

Test that the server is working:

# Test the built server
node build/index.js

# Should show: "Curl MCP Server running on stdio"
# Press Ctrl+C to exit

Troubleshooting

Common Issues

1. "Command not found" error

   • Ensure mcp-curl is installed globally: npm install -g @247arjun/mcp-curl

   • Or use npx: "command": "npx", "args": ["@247arjun/mcp-curl"]

2. "Permission denied" error

   • Check file permissions: chmod +x build/index.js

   • Rebuild the project: npm run build

3. MCP server not appearing in Claude

   • Verify JSON syntax in configuration file

   • Restart Claude Desktop completely

   • Check that the command path is correct

4. "curl command not found"

   • Install curl on your system (usually pre-installed on macOS/Linux)

   • Windows users: Install via package manager or download from curl website

Debugging

Enable verbose logging by setting environment variable:

# For development
DEBUG=1 node build/index.js

# Test with sample input
echo '{"jsonrpc": "2.0", "method": "initialize", "params": {}}' | node build/index.js

Security Notes

• Input validation and sanitization for all curl arguments

• Restricted file operations in advanced mode

• Safe subprocess execution using spawn instead of shell

• No arbitrary shell command execution

• Input validation with Zod schemas