Why3 MCP Server

by mrfentmen Your server? Claim it

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Why3 MCP runs on your own machine — the client starts it, so there is no endpoint to ping. Last commit 8 Nov 2026.

Why3 MCP: 20 real tools to read, check, lint, scaffold, build and run Why3 code.

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Installs / week

npm · @mrfentmen/why3-mcp

Stars

0 open issues

8 Nov 2026

Last commit

2 releases in 90 days

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License

TypeScript

Nothing serious here today

Today is the operative word: we check Why3 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 why3-mcp -- npx -y @mrfentmen/why3-mcp

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

{
  "mcpServers": {
    "why3-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/why3-mcp"
      ]
    }
  }
}

~/.codex/config.toml

[mcp_servers.why3-mcp]
command = "npx"
args = ["-y", "@mrfentmen/why3-mcp"]

.cursor/mcp.json

{
  "mcpServers": {
    "why3-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/why3-mcp"
      ]
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "why3-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@mrfentmen/why3-mcp"
      ]
    }
  }
}

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Why3 MCP — questions

Answers built from our own checks of this server.

Why is there no uptime for Why3 MCP?

Why3 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/why3-mcp.

How do I connect Why3 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/why3-mcp straight from npm; nothing to host, nothing to sign up for.

Is Why3 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.