DesyncedMCP

MCP server for Desynced mod development. Gives an AI assistant (Claude Code or any MCP client) direct access to the game's Lua API reference, base-game source, live game logs and installed mods.

Tools

Static (filesystem)

Live (lrdb debugger link, game running with -moddev)

The link speaks the satoren lrdb protocol (newline-delimited JSON-RPC, no init) against 127.0.0.1:21110. The game's debug server takes commands from a single client: while this server is linked, the in-game log console goes silent (output is redirected to the link) and VS Code cannot attach. The VM answers eval only while executing Lua, so an idle menu can time out.

Simulation bridge (companion mod)

game_eval runs in the game's UI Lua VM, where simulation mutations are blocked. Controlling the game (move, deploy, mine, construct...) requires the companion mod Desynced MCP Bridge on the Steam Workshop, which exposes FactionAction.MCPSimCmd into the simulation context. This server works without it for read-only tools (logs, status, eval reads, hot reload).

Setup

npm install
npm test   # smoke test

Register in Claude Code (project scope):

claude mcp add desynced --scope project -- node <path-to>/DesyncedMCP/server.js

Configuration (env vars)

Searching the base game (optional)

The game ships its entire base game as main.zip inside the mods folder and always loads it zipped — it is never extracted in a normal install. To let search_game_source and read_game_file see the base-game Lua, unzip main.zip into a main/ folder inside your workspace with any zip tool. This is purely a development convenience; the game neither needs nor uses the extracted copy.

Game-side requirements

The server itself runs outside the game — nothing to install in the game. For logs to exist, launch Desynced with these Steam launch options:

-moddev -log

-moddev enables the mod developer mode (hot reload with F7, strict data checks, log console); -log writes the log file this server reads.

Roadmap

• deploy_mod: copy a workspace mod into the game mods dir (replacing the manual copy step)
• Live bridge over the lrdb debug protocol (localhost:21110 in -moddev): eval Lua in the running game, inspect entities/factions, trigger Debug.Reload()
• Workshop publishing via DesyncedModUploader