Minecraft Dev MCP

A Model Context Protocol server that gives AI assistants native access to Minecraft mod development tools — decompile, remap, search, and analyze Minecraft source code directly from your AI workflow.

Quick Start

Prerequisites

Installation

Claude Desktop

Add to your Claude Desktop configuration file:

NPM installation:

{
  "mcpServers": {
    "minecraft-dev": {
      "command": "minecraft-dev-mcp"
    }
  }
}

NPX (no installation required):

{
  "mcpServers": {
    "minecraft-dev": {
      "command": "npx",
      "args": ["-y", "@mcdxai/minecraft-dev-mcp"]
    }
  }
}

Claude Code

Add to .claude/settings.local.json in your project, or to your global Claude Code settings:

{
  "mcpServers": {
    "minecraft-dev": {
      "command": "minecraft-dev-mcp"
    }
  }
}

HTTP Transport

For clients or editors that connect over HTTP instead of stdio, start the server in HTTP mode. It uses the MCP Streamable HTTP transport with per-session isolation.

minecraft-dev-mcp --http --port 3000

The MCP endpoint is http://<host>:<port>/mcp (POST to call, GET for the SSE stream, DELETE to end a session). Each client gets its own session, so multiple clients can connect concurrently.

Security: the default host 127.0.0.1 enables the SDK's DNS-rebinding protection automatically. Binding to a non-loopback host (e.g. --host 0.0.0.0) disables that protection — only do so on a trusted network, ideally behind a reverse proxy or auth.

CLI

A standalone CLI (minecraft-dev-cli) invokes the same tools directly — no MCP client required — for scripts, skills, and automation. Arguments are flags-only (--key value or --key=value) to avoid the JSON-quoting issues positional JSON arguments cause in PowerShell and other shells.

# List every tool with its parameters
minecraft-dev-cli list-tools

# Invoke a tool with flags
minecraft-dev-cli get_minecraft_source --version 1.21.10 --className net.minecraft.world.entity.Entity --mapping yarn

# Boolean / numeric / JSON values are coerced automatically
minecraft-dev-cli analyze_mod_jar --jarPath C:\mods\example.jar --includeAllClasses true

Output is always JSON: { "success": true, "tool": "...", "result": ... } on success, or { "success": false, "tool": "...", "error": "..." } with exit code 1 on failure. Run minecraft-dev-cli help for full usage.

Features

21 tools across 4 categories — see docs/tools.md for the full reference.

Common Workflows

Version Support

Yarn mappings are discontinued after 1.21.11, which is the last obfuscated Minecraft version. All 26.1+ releases ship with readable class and method names and only require Mojmap.

Tested versions: 1.19.4 · 1.20.1 · 1.21.10 · 1.21.11 · 26.1-snapshot-8 · 26.1-snapshot-9

Configuration

{
  "mcpServers": {
    "minecraft-dev": {
      "command": "minecraft-dev-mcp",
      "env": {
        "CACHE_DIR": "/custom/cache/path",
        "LOG_LEVEL": "DEBUG"
      }
    }
  }
}

Cache Location

Downloaded JARs, mappings, decompiled source, and search databases live in a platform-specific cache directory shared across all workspaces (~400–500 MB per Minecraft version).

Delete the directory to clear the cache — the server re-downloads anything missing on next use. To relocate the cache anywhere on disk, set the CACHE_DIR environment variable (see Configuration).

Cache Contents

Development

Build from source:

git clone https://github.com/MCDxAI/minecraft-dev-mcp.git
cd minecraft-dev-mcp
npm install
npm run build

Troubleshooting

Credits