Alloy MCP Server

A local Model Context Protocol (MCP) server that provides a headless bridge between Claude Desktop and the Alloy Analyzer (Kodkod SAT solver). This allows Claude to write, compile, and execute formal verification models and read the raw mathematical graph structures directly back into its context window.

Features

• Fast Syntax Checking: Validates Alloy grammar without booting the heavy SAT solver.

• Targeted Execution: Isolate and test specific run or check commands.

• Raw Graph Extraction: Exposes the underlying atoms and relations (ans.toString()) so the AI can reason about the counterexample structurally.

• Black Box Logging: Automatically saves all system outputs and Java errors to a local text file for manual debugging.

Related MCP server: Claude Code Starter Kit MCP

Prerequisites

To run this server locally, you must have the following installed:

• Node.js (v18 or higher)

• Java Development Kit (JDK) (v11 or higher)

• Claude Desktop App

Installation & Setup

1. Clone the repository:

   git clone (https://github.com/joel6603/alloy-mcp-server.git)
   cd alloy-mcp-server

2. Install Node dependencies:

   npm install

3. Download the Alloy Engine: Download the official Alloy 6 .jar file from AlloyTools. Rename the file to org.alloytools.alloy.dist.jar. Place it directly in the root folder of this project.

4. Compile the Java Backend

   On Windows:

   javac -cp "org.alloytools.alloy.dist.jar;." RunAlloy.java

   On Mac/Linux:

   javac -cp "org.alloytools.alloy.dist.jar:." RunAlloy.java

5. Connecting to Claude Desktop: Windows: %APPDATA%\Claude\claude_desktop_config.json

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

   Add the server to your configuration, ensuring the absolute path points to where you cloned this repository:

   JSON { "mcpServers": { "alloy": { "command": "node", "args": [ "D:/path/to/your/repo/alloy-mcp-server/index.js" ] } } }

   Restart Claude Desktop completely.

   Available MCP Tools:

   check_alloy_syntax: Accepts raw .als code and instantly returns line/column syntax errors.

   run_alloy_model: Accepts raw .als code and an optional command_name. Executes the SAT solver and returns the resulting instances or counterexamples as formatted text.