TroteaTeodor/example-calculator-mcp

Example Calculator MCP Server

A simple Model Context Protocol (MCP) server that provides basic calculator tools. This server demonstrates how to create MCP tools and can be used as a template or for testing MCP deployment systems.

Features

This MCP server provides the following calculator tools:

• add - Add two numbers together
• subtract - Subtract second number from first number
• multiply - Multiply two numbers
• divide - Divide first number by second number (with zero division protection)
• power - Raise first number to the power of second number
• sqrt - Calculate square root of a number (with negative number protection)

Installation

1. Clone this repository
2. Install dependencies:

   npm install
   

Usage

Running the Server

HTTP Server (recommended for deployment):

npm start
# or explicitly
npm run start:http

Stdio Server (for Claude Desktop and local use):

npm run start:stdio

Development modes:

npm run dev          # HTTP server with auto-reload
npm run dev:stdio    # Stdio server with auto-reload

The HTTP server runs on port 8000 by default and includes:

• SSE endpoint at /sse for MCP communication
• Health check at /health
• Server info at /

The stdio version is for direct integration with Claude Desktop and other local MCP clients.

Example Tool Calls

When connected to an MCP client, you can use these tools:

Addition:

{
  "tool": "add",
  "arguments": {
    "a": 5,
    "b": 3
  }
}

Result: "5 + 3 = 8"

Division:

{
  "tool": "divide", 
  "arguments": {
    "a": 10,
    "b": 2
  }
}

Result: "10 ÷ 2 = 5"

Power:

{
  "tool": "power",
  "arguments": {
    "base": 2,
    "exponent": 3
  }
}

Result: "2^3 = 8"

Configuration

With Claude Desktop (Stdio)

Add to your Claude Desktop configuration:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "calculator": {
      "command": "node",
      "args": ["/path/to/example-calculator-mcp/src/index.js"]
    }
  }
}

With HTTP/SSE Transport

For web-based clients or deployment systems, use the HTTP server:

npm run start:http

Then connect to: http://localhost:8000/sse

With kagent.dev

This server is designed to work with kagent.dev deployment. Use:

python deploy_mcp.py github.com/your-org/example-calculator-mcp

The deployment script will automatically:

• Detect the Node.js project
• Use npm start (HTTP server)
• Set up proper health checks
• Create kagent ToolServer resources

Project Structure

example-calculator-mcp/
├── src/
│   └── index.js          # Main MCP server implementation
├── package.json          # Project configuration and dependencies
└── README.md            # This file

Error Handling

The server includes proper error handling for:

• Division by zero
• Square root of negative numbers
• Invalid tool names
• Missing or invalid arguments

Dependencies

• @modelcontextprotocol/sdk - Official MCP SDK for JavaScript/Node.js

License

MIT License - feel free to use this as a template for your own MCP servers.

Testing with kagent.dev

This server is designed to work with deployment systems like kagent.dev. The simple structure and standard npm scripts make it easy to containerize and deploy automatically.