mushroomTW

Rimworld Mod MCP — Testing skill for Claude Code

Testing community

Local-only MCP server for RimWorld modding: search the game's Defs and C# API, decompile installed mods, build mods, and test them in an isolated game session.

How to install Rimworld Mod MCP

This entry records only its repository, not the path inside it, so there is no exact command to give. Open mushroomTW/rimworld-mod-mcp and copy the folder into ~/.claude/skills/, or the file into ~/.claude/agents/.

What Rimworld Mod MCP does

Local-only MCP server for RimWorld modding: search the game's Defs and C# API, decompile installed mods, build mods, and test them in an isolated game session. Works with Claude Code, Codex, and any MCP client.

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README

rimworld-mod-mcp

A local-only [Model Context Protocol](https://modelcontextprotocol.io/) server that lets Claude Code, Codex, and other MCP clients research RimWorld's API and Defs, create and build mods, validate assets, and test them in an isolated game session.

This project is inspired by [Modmixer](https://github.com/lebek/modmixer) but is an independent implementation: it contains no Modmixer source code, does not depend on Modmixer, and never communicates with Modmixer or any other external service.

This project contains **no Steam Workshop publishing, uploading, or any external content transfer**.

[繁體中文](README_zh.md)

Highlights

Runs on Windows, macOS, and Linux; ships as a single dotnet tool.
Reads IL metadata directly to build the symbol index — roughly a hundred thousand symbols in seconds, with complete inheritance chains and real type signatures.
SQLite FTS5 full-text search over Defs, symbols, and decompiled source.
In-process decompilation via ICSharpCode.Decompiler. No external tools, no toolchain setup step.
Build failures return structured diagnostics (error code, file, line, column) instead of a wall of MSBuild output.
Tests mods with an isolated save folder and temporary directory links, leaving your real saves and settings untouched.
Merges diagnostics from the in-game bridge and Player.log. If the bridge cannot connect, Player.log still works and the reason is reported rather than silently degraded.
The bridge also reports in-game state (main menu vs. playing, map loaded, tick, paused, loading, open dialogs), so an agent can wait for the map to come up before judging a test instead of guessing from log silence.
The bridge ships prebuilt; run_test_cycle needs no local .NET SDK when the installed game matches the prebuilt version.
Game files, decompiled output, indexes, and diagnostics all stay on your machine.