MC Source MCP Server

An MCP server that allows you to explore and decompile Minecraft source code, specifically targeting versions released with unobfuscated mappings (e.g., experimental snapshots like 1.21.11_unobfuscated or 25w45a_unobfuscated).

Features

• List Versions: See available Minecraft versions, including special "unobfuscated" releases.
• Search Classes: Find class files within a specific version's JAR.
• Decompile: Decompile .class files on-the-fly using Vineflower (WASM) to view readable Java source code.
• Caching: Efficiently caches downloaded JARs and open ZIP file handles for performance.

Tools

list_versions

Lists available Minecraft versions.

• type: Filter by release, snapshot, or unobfuscated (recommended).
• limit: Number of versions to return.

search_classes

Searches for a class in a specific version.

• version: The version ID (e.g., 1.21.11_unobfuscated).
• query: The class name to search for (e.g., SharedConstants).

decompile_class

Decompiles a specific class.

• version: The version ID.
• className: The full path to the class (e.g., net/minecraft/SharedConstants).

Setup

npm install
npm run build

Usage

Configure your MCP client to run:

{
  "mcpServers": {
    "mcsrc": {
      "command": "node",
      "args": ["/path/to/mcsrc-mcp/dist/index.js"]
    }
  }
}

IDE Access from Windows (via HTTP/SSE)

If your IDE is running on Windows and cannot directly spawn the WSL process, you can run the server in HTTP mode.

1. Start the server in WSL:

   npm run start:http

   This will start an HTTP server on port 3000 (accessible as localhost:3000 from Windows).

2. Configure your MCP Client: Point your client to the Streamable HTTP endpoint:

   • URL: http://localhost:3000/mcp

   (No arguments needed for the client configuration, just the URL).