MCP Echo Test Server

A simple Model Context Protocol (MCP) server for testing parameter passing. This server echoes all input parameters unchanged, making it perfect for debugging and testing MCP integrations.

Features

• 🔄 Echo Tool: Returns all input parameters exactly as received
• 📊 Parameter Analysis: Shows parameter types and count
• 🔍 Debug Mode: Optional verbose logging for troubleshooting
• 📝 Server Info: Provides server capabilities and version information
• 🎯 Type Support: Handles strings, numbers, booleans, arrays, objects, and more

Installation

Via NPM (Recommended)

npm install -g mcp-echo-test-server

From Source

git clone https://github.com/yourusername/mcp-echo-test-server.git
cd mcp-echo-test-server
npm install
npm run build
npm link

Usage

With Cursor

Add to your Cursor settings (~/.cursor/mcp_settings.json or through Cursor Settings UI):

{
  "mcpServers": {
    "echo": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "mcp-echo-test-server"],
      "env": {
        "DEBUG": "false"
      }
    }
  }
}

With Claude Desktop

Add to your Claude configuration:

{
  "mcpServers": {
    "echo": {
      "command": "npx",
      "args": ["-y", "mcp-echo-test-server"],
      "env": {
        "DEBUG": "false"
      }
    }
  }
}

Enable Debug Mode

Set the DEBUG environment variable to "true" for verbose logging:

{
  "env": {
    "DEBUG": "true"
  }
}

Available Tools

1. echo

Echoes all input parameters unchanged. Perfect for testing parameter passing.

Parameters:

• string_param (optional): String parameter for testing
• number_param (optional): Number parameter for testing
• boolean_param (optional): Boolean parameter for testing
• array_param (optional): Array parameter for testing
• object_param (optional): Object parameter with any properties
• extra_params (optional): Additional parameters as key-value pairs
• Any other parameters are also accepted and returned

Example Response:

{
  "status": "success",
  "message": "Echo successful - parameters returned as received",
  "data": {
    "received_params": {
      "string_param": "test",
      "number_param": 42,
      "boolean_param": true
    },
    "param_count": 3,
    "param_types": {
      "string_param": "string",
      "number_param": "number",
      "boolean_param": "boolean"
    }
  },
  "timestamp": "2024-10-16T03:50:00.000Z"
}

2. server_info

Returns information about the MCP Echo Server.

Parameters: None

Example Response:

{
  "status": "success",
  "message": "MCP Echo Server Info",
  "data": {
    "name": "mcp-echo-test-server",
    "version": "1.0.0",
    "description": "A simple MCP server that echoes all input parameters",
    "capabilities": [
      "echo - Returns all input parameters unchanged",
      "server_info - Returns server information"
    ]
  },
  "timestamp": "2024-10-16T03:50:00.000Z"
}

Development

Project Structure

mcp-echo-test-server/
├── src/
│   ├── index.ts           # Business logic (EchoClient)
│   └── dotenv-silent.ts   # Silent environment variable loader
├── examples/
│   └── mcp-server.ts      # MCP server implementation
├── package.json
├── tsconfig.json
├── mcp.json               # MCP tool definitions
└── README.md

Build

npm run build

Test Locally

npm run test

Clean Build

npm run clean

Use Cases

1. Testing MCP Integration: Verify your MCP client setup is working correctly
2. Parameter Debugging: Understand how parameters are passed and received
3. Type Validation: Test different parameter types and structures
4. Protocol Learning: Learn how MCP servers work with a simple example
5. Troubleshooting: Use debug mode to diagnose connection issues

Technical Details

• Protocol: Model Context Protocol (MCP)
• Transport: Standard I/O (stdio)
• Communication: JSON-RPC 2.0
• Runtime: Node.js >= 16.0.0
• Language: TypeScript

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details

Author

Deng Pengfei

Support

For issues, questions, or suggestions, please create an issue on GitHub.