LOOT

Single Rust binary: a read-only MCP server using rmcp and libloot. It exposes LOOT-style output (masterlist-driven load order suggestion, plugin metadata YAML, general messages, Bash tags from plugin headers) — not Nexus API data.

Does not replace mutagen-mcp (records, FormIDs, compare) or mod-organizer-mcp (MO2 layout, plugins.txt). Use those for lists and deep plugin analysis; use loot_evaluate with paths from MO2 (especially game_local_path = active profile folder).

Version: see Cargo.toml (loot_server_info also returns the crate version at runtime).

Build (recommended: Docker)

This repo is meant to be built and run in a container (same toolchain as CI/production):

docker build -t loot-mcp .
# binary ends up in the image as /usr/local/bin/loot-mcp

Local cargo build --release works if you have a suitable Rust + libloot environment; the binary path is target/release/loot-mcp.

Run (stdio)

docker run -i --rm loot-mcp

The process speaks MCP over stdio (typical for Cursor and other MCP clients).

Environment variables

Variable	Purpose
LOOT_DATA_PATH	LOOT application data root (masterlists, prelude). Used when tool args omit loot_data_path.
LOOT_MCP_GAME_TYPE	Default game id (e.g. SkyrimSE) when the client omits game_type.
LOOT_MCP_GAME_PATH	Default game install root when the client omits game_path.
LOOT_MCP_GAME_LOCAL_PATH	Default profile folder (plugins.txt / loadorder.txt).
LOOT_MCP_MO2_MODS_PATH	MO2 mods directory; requires profile path and modlist.txt for priority order.
LOOT_MCP_CACHE	In-process prep cache for libloot game + plugin headers. Default 1 in the published Docker image; set 0 to disable.
LOOT_MCP_CACHE_TTL_SEC	Optional TTL (seconds) for cache entries when set to a positive value.
LOOT_MCP_TIMING	1 / true: print phase timings to stderr (loot-mcp timing: …).
LOOT_MCP_TIMINGS_JSON	1 / true: add a timings object to tool JSON responses (total_ms, prep_cache, per-phase ms).
LOOT_MCP_DIAGNOSTICS_LOG	Absolute path to an NDJSON file; appends one JSON object per begin/end (and errors). In Docker, bind-mount a host directory and point this path inside the container.
LOOT_MCP_PARALLEL_METADATA	Set to 0 to disable parallel per-plugin metadata evaluation (default is parallel).

Cursor MCP config

Docker (typical)

Use paths as seen inside the container in tool arguments (e.g. game_path: "/game", game_local_path: "/profile").

{
  "mcpServers": {
    "loot-mcp": {
      "command": "docker",
      "args": [
        "run", "--rm", "-i",
        "-v", "/path/to/Skyrim Special Edition:/game:ro",
        "-v", "/path/to/MO2/profiles/MyProfile:/profile:ro",
        "-v", "/path/to/MO2/mods:/mods:ro",
        "-v", "/path/to/LOOT AppData:/loot:ro",
        "-e", "LOOT_DATA_PATH=/loot",
        "-e", "LOOT_MCP_GAME_TYPE=SkyrimSE",
        "-e", "LOOT_MCP_GAME_PATH=/game",
        "-e", "LOOT_MCP_GAME_LOCAL_PATH=/profile",
        "-e", "LOOT_MCP_MO2_MODS_PATH=/mods",
        "-e", "LOOT_MCP_CACHE=1",
        "-e", "LOOT_MCP_TIMINGS_JSON=1",
        "-e", "LOOT_MCP_DIAGNOSTICS_LOG=/logs/loot-mcp-diagnostics.ndjson",
        "-v", "/path/on/host/mcp-logs/loot:/logs",
        "loot-mcp"
      ]
    }
  }
}

Adjust host paths and image tag (loot-mcp, loot-mcp:local, etc.). Omit LOOT_MCP_TIMINGS_JSON / LOOT_MCP_DIAGNOSTICS_LOG / the logs volume if you do not need diagnostics.

Local binary

{
  "mcpServers": {
    "loot": {
      "command": "/absolute/path/to/loot-mcp"
    }
  }
}

Container one-liner (manual test)

docker build -t loot-mcp .
docker run -i --rm \
  -v "/path/to/Game:/game:ro" \
  -v "/path/to/MO2/Profile:/profile:ro" \
  -v "/path/to/MO2/mods:/mods:ro" \
  -v "/path/to/LOOT:/loot:ro" \
  -e LOOT_DATA_PATH=/loot \
  -e LOOT_MCP_GAME_TYPE=SkyrimSE \
  -e LOOT_MCP_GAME_PATH=/game \
  -e LOOT_MCP_GAME_LOCAL_PATH=/profile \
  -e LOOT_MCP_MO2_MODS_PATH=/mods \
  loot-mcp

The image sets ENV LOOT_MCP_CACHE=1 so repeated tools in one container reuse prep when signatures match.

Tools

• loot_evaluate — Main evaluation: load_order_current, optional load_order_suggested, general_messages, optional per-plugin metadata. Required MCP args: game_type, game_path (defaults can come from env above). Useful flags: include_load_order_suggested: false skips sorting (faster); include_plugin_metadata: true with plugin_metadata_content: "problems" returns only plugins with LOOT issues (warn/error messages, incompatibilities, optional requirements/load_after); general_messages_min_severity: say | warn | error; pagination via plugin_metadata_offset / plugin_metadata_limit; include_master_header_issues. On failure, JSON includes error and the MCP result is an error.
• loot_load_order — Reads loadorder.txt or plugins.txt from game_local_path (fast). Optional load_order_use_libloadorder: true forces libloadorder (slower with many MO2 paths). Same path/env defaults as loot_evaluate.
• loot_plugin_metadata — Evaluated metadata for an explicit list of plugin names; same base arguments as loot_evaluate (flattened), plus plugin_names.
• loot_server_info — Crate version, libloot version/revision, executable path.

Notes

general_messages vs per-plugin messages

general_messages are global LOOT messages (prelude / masterlist “general” section) — usually a small count. Most masterlist text is per plugin; use include_plugin_metadata and plugin_metadata_content: "problems" or "full" to see it.

WSL / Linux

Game and profile paths must be readable inside the process (e.g. /mnt/c/... or distro mounts). libloot behavior matches upstream LOOT for supported games.