Calculator MCP Server

A comprehensive calculator implemented as a Model Context Protocol (MCP) server using TypeScript.

This server exposes a wide range of mathematical functions as MCP tools, allowing language models connected via MCP clients (like Claude for Desktop, Cursor, etc.) to perform calculations.

Features

Provides MCP tools for:

• Basic Arithmetic: Addition, Subtraction, Multiplication, Division
• Exponents & Roots: Power (^), Square Root
• Trigonometry: Sine, Cosine, Tangent (input in radians)
• Inverse Trigonometry: Arcsine, Arccosine, Arctangent, Arctan2 (output in radians)
• Degree/Radian Conversion: Convert between degrees and radians
• Logarithms: Natural Log (ln), Base-10 Log (log10), Log with arbitrary base
• Constants: Pi (π), Euler's number (e)
• Factorial: n!
• Percentage: Calculate percentage of a number
• Modulo: Remainder operation
• Absolute Value: abs()
• Rounding: Floor, Ceiling, Round to nearest integer

Prerequisites

• Node.js (v16 or higher recommended)
• npm (usually included with Node.js)

Installation

1. Clone the repository:

   git clone https://github.com/mvavassori/calculator-mcp-server.git
   

2. Navigate into the project directory:

   cd calculator-mcp-server
   

3. Install dependencies:

   npm install
   

Running the Server

1. Build the TypeScript code:

   npm run build
   

   This compiles the code into the build directory.

2. Run the server:

   npm run start
   # OR directly using node:
   # node build/index.js
   

The server will start and listen for MCP connections via standard input/output (stdio). You should see a message like Calculator MCP Server connected via stdio and ready. printed to your terminal's standard error. Keep this terminal window open while using the server with Claude Desktop.

Connecting to Clients (Claude Desktop Example)

This server communicates using the MCP stdio transport. To connect it to Claude for Desktop:

1. Find Claude Desktop's MCP Configuration File:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json (You can paste this path into the File Explorer address bar).
   • Linux: ~/.config/Claude/claude_desktop_config.json
   • If the file or the Claude directory doesn't exist, you might need to create it, or open Claude Desktop's Settings (Claude Menu > Settings... > Developer > Edit Config) which should create the file for you.

2. Edit the Configuration File: Open the claude_desktop_config.json file in a text editor.

3. Add the Server Configuration: Modify the file to include the mcpServers object with your calculator server entry. If the file was empty or didn't exist, its entire content should look like this:

   {
     "mcpServers": {
       "calculator": {
         "command": "node",
         "args": [
           "/home/marco/code/calculator-mcp-server/build/index.js"
           // IMPORTANT: Replace this path with the ACTUAL ABSOLUTE PATH
           // to the 'build/index.js' file on YOUR system.
         ]
       }
       // You can add other servers here under different keys, like:
       // "another_server": { ... }
     }
   }
   

   Notes:

   • CRITICAL: Replace /home/marco/code/calculator-mcp-server/build/index.js with the correct absolute path to the build/index.js file within your cloned project directory on your computer.
   • On Windows, use double backslashes (\\) for the path separators, e.g., "C:\\Users\\YourUser\\path\\to\\calculator-mcp-server\\build\\index.js".
   • The key "calculator" is just a name you give this server connection within Claude's config; it can be anything descriptive.
   • If the mcpServers object already exists, just add the "calculator": { ... } entry inside it, separated by a comma if other servers are present.

4. Restart Claude for Desktop: Ensure Claude for Desktop is fully closed and reopened for the new configuration to take effect.

Claude for Desktop should now show the MCP tools icon (a hammer ) and be able to use the calculator tools when you ask it to perform calculations.

License

MIT License