# Cruncher [Health: Active]

**Category:** 🧮 Data Science Tools  
**Repository:** https://github.com/islobodan/cruncher-mcp  
**GitHub Stars:** 1  
**npm Downloads (last month):** 174  
**Views:** 1  
**Installs:** 0  
**Upvotes:** 0  
**Directory Page:** https://allmcps.com/mcp/cruncher

## Description
Scientific calculator MCP server with 43 tools: arithmetic, trig, stats, unit conversion.

## Claude Desktop Quick Installation
Install path detected from listing signals. Uses `npx` (confidence: high):

```json
"mcpServers": {
  "cruncher": {
    "command": "npx",
    "args": ["-y","@slbdn/cruncher-mcp"],
    "env": {
      "CRUNCHER_TIMEOUT": "",
      "CRUNCHER_TOOL_SET": ""
    }
  }
}
```

**Requires environment variables:** `CRUNCHER_TIMEOUT`, `CRUNCHER_TOOL_SET` — the values above are empty placeholders; fill in real credentials before running (see the repository for what each one is for).

## Documentation

## What Cruncher does

The Cruncher MCP server exposes scientific calculator functions to MCP-compatible AI clients. Its tools cover basic arithmetic, complete expression evaluation, powers, square roots, factorials, trigonometric functions, logarithms, percentages, statistics, constants, and absolute values. Trigonometric operations accept degrees or radians.

Statistical tools operate on arrays of numbers and include sum, average, median, minimum, maximum, range, count, variance, and standard deviation. Unit conversion supports more than 80 conversions across length, weight, temperature, area, volume, time, speed, and digital storage. The full tool tier also provides calculator-style memory operations: add to memory, subtract from memory, recall, and clear.

## How it works

Cruncher runs as a stdio MCP server implemented in plain JavaScript and uses Node.js standard libraries rather than the official MCP SDK or external math packages. It handles MCP initialization, tool discovery, tool calls, JSON-RPC messages, input validation, and error formatting directly in the application.

Expression evaluation is restricted by a whitelist so accepted input contains numbers and supported mathematical operators rather than arbitrary JavaScript. Calculations run in worker threads, allowing the main process to stop work that exceeds the configured timeout. Decimal operations use integer scaling to reduce common floating-point errors such as the usual JavaScript result for 0.1 + 0.2.

## Setup and configuration

Node.js 18 or newer is required. The npm package can be started with `npx @slbdn/cruncher-mcp`, or the `cruncher.js` file can be run directly with Node.js. MCP clients need a stdio configuration with either `npx` and the package name or `node` and the script path.

The Cruncher MCP server supports three tool exposure levels: `minimal`, `standard`, and `full`. `standard` is the default and can be selected with `CRUNCHER_TOOL_SET`. Set `CRUNCHER_TIMEOUT` to change the calculation timeout in milliseconds; the documented default is three seconds.

The README provides configuration examples for Claude Desktop, Cursor, and Cline, and also documents stdio setup for OpenWebUI. After changing a client configuration, restart the client so it reconnects to the server.

## Tools and capabilities

- Arithmetic: addition, subtraction, multiplication, division, and modulo
- Expressions, powers, roots, factorials, and absolute values
- Trigonometry in degrees or radians
- Base-10 and natural logarithms
- Array statistics and percentage calculations
- Mathematical, physical, and chemical constants
- More than 80 unit conversions in eight categories
- Memory operations in the full tool tier
- Tiered tool exposure to control context usage

## Limitations and notes

Heavy or very large calculations can be terminated when they exceed the timeout. Memory functions are available only in the full tier. Running the server requires Node.js 18 or newer.

_Full upstream README: https://allmcps.com/mcp/cruncher/readme_