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Cruncher MCP server

by islobodan·io.github.islobodan/cruncher-mcp·v1.2.29·1 stars
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Scientific calculator MCP server with 43 tools: arithmetic, trig, stats, unit conversion.

B80/100grade B
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Safety scan
B80/100

full report

Adoption
Growing

1 stars51 downloads/wk

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If you have run it, two minutes of your experience saves the next person an afternoon.

Cruncher tools

No tool declarations could be read from the package source. They show once the server is installed.

Public scan report

scanner v0.1.9 · 2026-09-27 · same rubric, same numbers if you re-run it

1 medium
  • Code scan3 source files scanned20/25
  • –Live reliabilityno gateway calls yet and no remote to proben/a
  • –Tool poisoningtools not inspected (local package is not executed); not countedn/a
  • Auth qualitylocal package, no credentials required12/15
  • Maintenancelast push 89 days ago12/15
  • Maintainer identityregistry namespace matches repository owner; GitHub account older than a year8/10

Findings (1)

  • mediumeval / new Function usedexec.eval
    cruncher.js: …safe to run. const result = new Function("return (" + parsedExpr + ")")(); …
Overall 80/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Cruncher compares

Against every graded MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
80/100
higher than 60% of 48,255 servers
GitHub stars
1
more than 65% of 28,688 servers
Downloads a week
51
more than 43% of 12,191 servers with a package

Install Cruncher in Claude Code, Cursor or VS Code

Runs npx -y @slbdn/cruncher-mcp on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add cruncher-mcp -- npx -y @slbdn/cruncher-mcp
Add to Cursor

What the publisher says

From the Cruncher repository's README, as published. We do not edit it. Read it on GitHub

Cruncher: The Scientific Calculator MCP Server

A powerful scientific calculator for your AI assistant, built as a Model Context Protocol (MCP) server. Cruncher allows compatible AI clients (like Claude Desktop) to perform complex mathematical calculations, handle memory, perform statistical analysis, and access scientific constants with a simple, secure, and standardized interface.

🌟 The Purity Promise (Zero Dependencies)

Cruncher is built as a highly educational, extremely lightweight tool. It accomplishes powerful features without pulling in any heavy external libraries (no mathjs, no zod, no @modelcontextprotocol/sdk). Everything is handled using native Node.js capabilities:

  • Safe Expression Evaluation: Instead of relying on mathjs or dangerous eval(), Cruncher uses new Function() guarded by a strict whitelist Regex that guarantees only numbers and math operators can pass.
  • Input Validation: Instead of heavy schema libraries like Zod, a custom recursive validation function rigidly enforces AI inputs against JSON Schemas directly.
  • Timeout Protection: Instead of complex process managers, it leverages Node.js workerthreads to spawn calculations. If an AI requests a multi-million loop factorial, the main thread easily terminates the worker after a strict timeout (default 3 seconds). This timeout is configurable via the CRUNCHERTIMEOUT environment variable (in milliseconds), ensuring the server remains responsive even during heavy computational loads.
  • Floating-Point Accuracy: Instead of using decimal.js, it solves the classic JS math error (0.1 + 0.2 = 0.30000000000000004) via dynamic integer-scaling logic under the hood.

📚 An Educational Approach to MCP

This project serves as an excellent learning resource for developers looking to understand the Model Context Protocol (MCP) deeply. Because it deliberately avoids using the official @modelcontextprotocol/sdk, the entire implementation of the MCP protocol, JSON-RPC message handling, input validations, and error formatting is exposed in plain JavaScript.

Reading through cruncher.js provides unparalleled, transparent insight into exactly how an MCP server communicates over stdio, parses incoming requests (initialize, tools/list, tools/call), and responds back to the AI client-demystifying the "magic" that SDKs usually hide away.

What is the Model Context Protocol?

The Model Context Protocol (MCP) is an open standard that allows AI applications to securely connect with external data sources and tools. Think of it as a universal API for AI. By implementing Cruncher as an MCP server, any AI that understands MCP can instantly gain powerful, built-in calculator capabilities without custom integrations.

✨ Features

Cruncher provides a comprehensive set of calculator functions built completely from scratch without heavy dependencies:

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Cruncher: common questions

Is Cruncher MCP server safe?
Mostly: it is graded B (80/100). Read the Cruncher safety report
How do I install Cruncher?
It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Cruncher need an API key?
No secret keys are declared. It reads 2 settings from the environment.
Is Cruncher maintained?
The last commit was 126 days ago (2026-06-30). The latest release is v1.2.29.
How does Cruncher compare with other MCP servers?
safety score 80/100 (higher than 60% of 48,255 servers); github stars 1 (more than 65% of 28,688 servers); downloads a week 51 (more than 43% of 12,191 servers with a package). Full comparison.