---
title: "LeanTool"
description: "Connects LLMs to Lean 4 for real-time syntax checking and error correction in theorem proving code."
category: "mcp-servers"
tags: ["utility", "api", "server", "data", "real-time", "LLM", "syntax validation", "error feedback", "theorem proving"]
tech_stack: ["Lean 4", "Theorem Proving", "Formal Verification", "Interactive Theorem Provers", "Large Language Models"]
---

LeanTool acts as a bridge between large language models and the Lean 4 programming environment. It creates a communication channel that enables LLMs to interact directly with Lean's code interpreter. This connection allows for real-time syntax validation and immediate error feedback.

Why does this matter? Lean 4’s syntax and library ecosystem change quickly, often outpacing what LLMs learn during training. LeanTool helps LLMs keep up by letting them test and refine their Lean code through iterative execution. This process enhances code accuracy and cuts down on the time spent on manual debugging.

Developers can leverage LeanTool in various ways. It can assist with automated theorem proving, help create educational tools, and support reliable code generation in formal verification workflows. Essentially, this tool offers a code interpreter pattern that fits perfectly with interactive theorem proving in Lean 4.