Calculator MCP Server

A simple Model Context Protocol (MCP) server that provides basic calculator functionality through MCP tools.

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 together
• 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. Install dependencies:

npm install

1. Build the TypeScript code:

npm run build

Usage

Running the Server

Start the MCP server:

npm start

Or run in development mode:

npm run dev

MCP Client Configuration

To use this calculator MCP server with an MCP client (like Claude Desktop), add it to your MCP configuration:

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

Available Tools

add

Adds two numbers together.

• Parameters: a (number), b (number)
• Example: add(5, 3) returns 5 + 3 = 8

subtract

Subtracts the second number from the first.

• Parameters: a (number), b (number)
• Example: subtract(10, 4) returns 10 - 4 = 6

multiply

Multiplies two numbers together.

• Parameters: a (number), b (number)
• Example: multiply(6, 7) returns 6 × 7 = 42

divide

Divides the first number by the second.

• Parameters: a (number), b (number)
• Example: divide(15, 3) returns 15 ÷ 3 = 5
• Error handling: Returns error for division by zero

power

Raises the base to the power of the exponent.

• Parameters: base (number), exponent (number)
• Example: power(2, 8) returns 2^8 = 256

sqrt

Calculates the square root of a number.

• Parameters: number (number)
• Example: sqrt(16) returns √16 = 4
• Error handling: Returns error for negative numbers

Development

Project Structure

calculator-mcp/
├── src/
│   └── index.ts          # Main MCP server implementation
├── dist/                 # Compiled JavaScript output
├── package.json          # Dependencies and scripts
├── tsconfig.json         # TypeScript configuration
└── README.md            # This file

Building

npm run build

Development Mode

npm run dev

Error Handling

The calculator includes proper error handling for:

• Division by zero
• Square root of negative numbers
• Invalid tool names
• General execution errors

All errors are returned with appropriate error messages and the isError flag set to true.

License

MIT