PackWarden — Thunderstore Mod-Pack MCP Server (v0.1.0)

PackWarden is not affiliated with or endorsed by Thunderstore. "Thunderstore" is used only to describe compatibility. Mod data comes from the public Thunderstore API (https://thunderstore.io).

An MCP server that helps AI assistants build and maintain Thunderstore mod packs (Lethal Company, Risk of Rain 2, Valheim, and every other Thunderstore community).

Tools

Tool	What it does
list_communities	List Thunderstore game communities (identifier + name).
search_mods	Search a community by name/owner/description/category; sort by relevance, downloads, rating, updated.
resolve_dependencies	Full transitive dependency closure for one or more packages/versions; final install set, missing deps, multi-version pins, optional tree.
check_pack_health	Audit a mod list: not found, removed version, deprecated, outdated, missing deps, dependency version conflicts, duplicates, NSFW.
export_r2modman_profile	Write an .r2z profile (r2modman / Thunderstore Mod Manager "Import profile → From file"), optionally with deps and config files. Nothing is uploaded.

Mods are referenced as Owner-Name (latest) or Owner-Name-1.2.3.

Install

Requires Node.js ≥ 18.17.

git clone <repo> thunderstore-mcp && cd thunderstore-mcp
npm install && npm run build

Claude Desktop

Edit claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\):

{
  "mcpServers": {
    "thunderstore": {
      "command": "node",
      "args": ["/absolute/path/to/thunderstore-mcp/dist/main.js"],
      "env": { "TSMCP_EXPORT_DIR": "/absolute/path/for/profiles" }
    }
  }
}

Restart Claude Desktop.

Cursor

~/.cursor/mcp.json (global) or .cursor/mcp.json (project):

{
  "mcpServers": {
    "thunderstore": {
      "command": "node",
      "args": ["/absolute/path/to/thunderstore-mcp/dist/main.js"]
    }
  }
}

Streamable HTTP (remote / self-hosted)

npm run start:http            # http://127.0.0.1:3333/mcp
PORT=8080 HOST=0.0.0.0 node dist/main.js --http

Cursor: { "mcpServers": { "thunderstore": { "url": "http://127.0.0.1:3333/mcp" } } }. The HTTP mode is stateless (POST-only, JSON responses) and has no auth. Put it behind a reverse proxy with TLS and auth before exposing it.

Configuration (env)

Var	Default	Meaning
TSMCP_CACHE_DIR	~/.cache/thunderstore-mcp	Slim package-index cache
TSMCP_LIST_TTL_MS	3600000 (1h)	Package-list freshness
TSMCP_MIN_INTERVAL_MS	1000	Minimum gap between outbound requests
TSMCP_EXPORT_DIR	./exports	Where .r2z files are written
TSMCP_CONTACT	[email protected]	Contact put in the User-Agent. Override if you run your own copy.
TSMCP_BRAND	PackWarden	Brand in server name/User-Agent
TSMCP_BASE_URL	https://thunderstore.io	API base

Be a good API citizen

• One full package list download per community per TTL, then conditional requests (If-Modified-Since). Results are cached on disk as a slim index.
• Outbound requests are serialized (concurrency 1) and spaced ≥1s apart. On 429/5xx the client backs off and honours Retry-After.
• Identifying User-Agent with a contact address.
• If the network fails, the server keeps serving stale cache.

Tests (live API)

npm test                         # default community: valheim
TEST_COMMUNITY=valheim npm test

Tests cover stdio and streamable HTTP end-to-end against the live Thunderstore API.

Limitations

• Large communities are heavy. The first load of Lethal Company is about 330 MB of JSON, takes about 14 s, and uses about 1.4 GB of RAM. After that, loads from cache take about 3 s.
• Resolution follows r2modman behaviour (highest requested version wins). It does not do semver range solving, because Thunderstore pins exact versions.
• No profile code sharing, which would need an upload to Thunderstore. Only file export is supported.
• Search is local keyword scoring, not Thunderstore's own search ranking.