Lean 4 MCP Server

by mrfentmen Your server? Claim it

local only

Lean 4 MCP runs on your own machine — the client starts it, so there is no endpoint to ping. Last commit 8 Nov 2026.

Lean 4 MCP: 20 real tools to read, check, lint, scaffold, build and run Lean 4 code.

—

Installs / week

npm · @mrfentmen/lean-4-mcp

Stars

0 open issues

8 Nov 2026

Last commit

2 releases in 90 days

—

License

TypeScript

Nothing serious here today

Today is the operative word: we check Lean 4 MCP every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add lean-4-mcp -- npx -y @mrfentmen/lean-4-mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "lean-4-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/lean-4-mcp"
      ]
    }
  }
}

~/.codex/config.toml

[mcp_servers.lean-4-mcp]
command = "npx"
args = ["-y", "@mrfentmen/lean-4-mcp"]

.cursor/mcp.json

{
  "mcpServers": {
    "lean-4-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/lean-4-mcp"
      ]
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "lean-4-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/lean-4-mcp"
      ]
    }
  }
}

Alternatives to Lean 4 MCP

same job, measured the same way

Clean MCP

by mrfentmen

Clean MCP: 20 real tools to read, check, lint, scaffold, build and run Clean code.

local only

Leo MCP

by mrfentmen

Leo MCP: 20 real tools to read, check, lint, scaffold, build and run Leo code.

local only

4d MCP

by mrfentmen

4D MCP: 20 real tools to read, check, lint, scaffold, build and run 4D code.

local only

Lex MCP

by mrfentmen

Lex MCP: 20 real tools to read, check, lint, scaffold, build and run Lex code.

local only

M MCP

by mrfentmen

M MCP: 20 real tools to read, check, lint, scaffold, build and run M code.

local only

B MCP

by mrfentmen

B MCP: 20 real tools to read, check, lint, scaffold, build and run B code.

local only

C MCP

by mrfentmen

C MCP: 20 real tools to read, check, lint, scaffold, build and run C code.

local only

R MCP

by mrfentmen

R MCP: 20 real tools to read, check, lint, scaffold, build and run R code.

local only

Lean 4 MCP — questions

Answers built from our own checks of this server.

Why is there no uptime for Lean 4 MCP?

Lean 4 MCP runs on your own machine over stdio — there is no network address to reach, so uptime cannot be measured for it by anyone. What can be measured is adoption: the npm package @mrfentmen/lean-4-mcp.

How do I connect Lean 4 MCP?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It runs locally, so the command pulls @mrfentmen/lean-4-mcp straight from npm; nothing to host, nothing to sign up for.

Is Lean 4 MCP open source?

We cannot say either way: written in TypeScript and 0 stars on GitHub, but we could not determine the licence, and without one the code is not open source by default.