RimSage is an MCP server that lets you search RimWorld source code, read specific files, inspect definitions, and read C# symbol details through a standardized MCP interface. You can run RimSage locally using Bun in stdio mode, or connect to the online service at the provided URL. The server exposes tools such as search_rimworld_source for code search, read_rimworld_file to fetch file contents, list_directory to explore repo structure, search_defs to query RimWorld Defs, get_def_details to retrieve def XML, and read_csharp_symbol to inspect C# types and methods. To use these tools, point your MCP client (or integration code) at RimSage via the mcp.json configuration or the stdio transport, and issue the corresponding tool requests. The server supports both local stdio transport and a streamable HTTP option when started with bun run start:http for easier integration with frontends or agents.

For self-hosted usage, configure the mcp.json to reference the local repository and start RimSage through Bun. Example mcp.json for local stdio: { "mcpServers": { "rimsage": { "command": "bun", "args": ["run", "/path/to/this/repo"] } } }

Prerequisites:

• Bun runtime installed (https://bun.sh/)
• Ripgrep installed (rg)

Installation and setup steps:

1. Clone the RimSage repository: git clone https://github.com/realloon/RimSage.git
2. Install dependencies: bun install
3. Build the index data and any necessary assets (requires RimWorld data and decompiled C# sources): bun run src/scripts/import-defs /path/to/your/rimworld/root/path bun run src/scripts/import-csharp /path/to/decompiled/source/root/path bun run build
4. Run the server in stdio mode (local development): bun run start

   or for a streamable HTTP interface:

   bun run start:http
5. Add the MCP integration for your environment (examples below).

Notes:

• You must have local RimWorld files and a decompiled C# project available where the importer scripts can access them. This is required to build the search indexes used by RimSage.
• This workflow is compliant with RimWorld EULA when you host your own copies for development.

Tips and caveats:

• The server relies on local RimWorld data; ensure the paths you provide to the importer scripts are correct and accessible.
• If you encounter performance issues, ensure your machine has sufficient RAM for indexing and a fast disk for index storage.
• The online service URL is provided for quick access; self-hosted usage requires configuring mcp.json or using stdio transport via Bun.
• Environment variables are not required by default, but you can set additional flags or tokens if you extend the server configuration for authentication or logging.
• When using stdio transport, replace /path/to/this/repo with the actual path to the RimSage repository on your system.