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)

Tool	Purpose
search_lua_api	Search the official Lua API reference (vendored in docs/lua-api.txt)
search_game_source	Regex search over base game (main/) + mods Lua/JSON in the workspace
get_game_logs	Tail a game log file if one exists (see -abslog note below)
list_mods	List mods the game will load vs. mods in the workspace
read_game_file	Read any workspace source file by relative path with line range

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

Tool	Purpose
game_status	Live snapshot: tick, player faction, entity count, active mod settings
game_logs	Output captured live (print/errors/BOOT); survives crashes up to the moment of death
game_eval	Execute arbitrary Lua inside the running game and return the result
game_reload	Debug.Reload() — hot reload all mod Lua, exactly like pressing F7

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)

Var	Default
DESYNCED_WORKSPACE	current working directory — point it at the folder holding your mod sources
DESYNCED_GAME_MODS	C:/Program Files (x86)/Steam/steamapps/common/Desynced/Desynced/Content/mods — set it if Steam lives elsewhere (custom library folder)
DESYNCED_SAVED	%LOCALAPPDATA%/Desynced/Saved

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