My JavaScript MCP Server

A Model Context Protocol (MCP) server built with JavaScript that provides basic tools and resources.

Features

Tools

• echo: Echo back any message
• calculate: Perform basic arithmetic operations (add, subtract, multiply, divide)
• get_system_info: Get basic system information

Resources

• package.json: Access to the server’s package configuration

Installation

1. Make sure you have Node.js installed
2. Install dependencies:

   npm install
   

Usage

Running the Server

npm start

Development Mode

npm run dev

Testing with MCP Inspector

You can test your server using the MCP Inspector:

npx @modelcontextprotocol/inspector node server.js

Configuration

This server runs on stdio transport, which means it communicates through standard input/output. This is the most common way to run MCP servers.

Example Usage

Once connected to an MCP client, you can:

1. Echo a message:

   • Tool: echo
   • Parameters: {"message": "Hello, World!"}

2. Perform calculations:

   • Tool: calculate
   • Parameters: {"operation": "add", "a": 5, "b": 3}

3. Get system information:

   • Tool: get_system_info
   • Parameters: {}

4. Read resources:

   • Resource: file://package.json

Extending the Server

To add new tools or resources:

1. Add tool definitions to the ListToolsRequestSchema handler
2. Add tool logic to the CallToolRequestSchema handler
3. Add resource definitions to the ListResourcesRequestSchema handler
4. Add resource reading logic to the ReadResourceRequestSchema handler

Error Handling

The server includes proper error handling for:

• Division by zero in calculations
• Unknown tools and resources
• File reading errors
• Graceful shutdown on SIGINT