# calc-mcp

calc-mcp gives AI coding clients local tools for calculations, dates, encoding, hashes, and random values. Use it when repeatable results matter.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 9
- Author: coo-quack
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/coo-quack/calc-mcp
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/calc-mcp

## What it does

calc-mcp exposes 21 MCP tools covering arithmetic, date handling, encoding, hashing, randomness, conversions, and data parsing. The server can evaluate expressions, inspect time zones, create UUIDs, transform colors and units, validate JSON, and parse URLs or JWTs.

Processing stays on the local machine, so the tools do not send data to external services. Setup runs the package with `npx`, and Node.js is required. Without Node.js, the server will not start.

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add calc-mcp -- npx -y @coo-quack/calc-mcp
```

### Codex

**Platform CLI**
```bash
codex mcp add calc-mcp -- npx -y @coo-quack/calc-mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "calc-mcp": {
            "command": "npx",
            "args": [
                "-y",
                "@coo-quack/calc-mcp"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "calc-mcp": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@coo-quack/calc-mcp"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add calc-mcp npx -y @coo-quack/calc-mcp
```

## When to use it
- check an expression without relying on model arithmetic
- create a random UUID or test password
- convert a date across time zones
- encode, decode, or hash a value
- inspect a URL, JWT, or JSON document

## Example prompts
- Calculate this expression and return the exact result.
- Generate a UUID v7 and a random password for my test data.
- Validate this JSON, decode the JWT, and show its fields.

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