steam-mcp

steam-mcp is a Windows-first local MCP server for working with a Steam library safely. It gives MCP clients a practical way to inspect a local Steam setup, search owned games, enrich results with Steam Deck and store data, generate links, and plan collection changes before any write step.

What it can do

• Inspect the active Steam environment and selected user with steam_status
• List and filter owned games with steam_library_list
• Search the local library with steam_library_search
• Search the public Steam store with steam_store_search
• Query the authenticated official Steam catalog with steam_store_query
• Scout authenticated featured/editorial Steam marketing placements with steam_featured_scout
• Scout upcoming or newly released Steam catalog apps with steam_release_scout
• List recently played games with steam_recently_played
• List selected-user wishlist items currently on sale with steam_wishlist_on_sale, derived from official wishlist data plus live public appdetails price metadata
• Enrich, search, Deck-shortlist, and summarize discounts for selected-user wishlist items with steam_wishlist_details, steam_wishlist_search, steam_wishlist_deck_shortlist, and steam_wishlist_discount_summary
• Find similar games with deterministic ranking by default and optional official store prioritization via steam_find_similar
• Export results as JSON or Markdown with steam_export
• Generate steam:// and web links with steam_link_generate
• Preview collection and hidden-state changes with steam_collection_plan
• Apply a reviewed collection plan with steam_collection_apply when writes are explicitly enabled, using a staged cloudstorage apply flow

Safety model

• Read-heavy by default
• steam_collection_apply is the only tool that mutates Steam-owned state
• Steam-owned writes stay disabled unless STEAM_ENABLE_COLLECTION_WRITES=1; treat this as the explicit write-unlock / operator kill switch for Steam-owned mutations
• STEAM_ENABLE_WINDOWS_ORCHESTRATION=1 is a separate Windows-only opt-in wrapper that can best-effort launch Steam on MCP startup and close Steam before each apply call; after a successful dirty-only apply it leaves Steam closed, and after a finalize apply or a failed apply it best-effort relaunches Steam only if the wrapper stopped it
• steam_collection_plan creates durable preview plans under MCP-owned state without mutating Steam-owned data
• Apply is backup-first, drift-checked, rollback-capable, and requires Steam to be closed; orchestration satisfies that precondition on supported Windows runtimes
• Staged sync is JSON-only for cloudstorage files: cloud-storage-namespace-1.json, cloud-storage-namespace-1.modified.json, and cloud-storage-namespaces.json
• Staged sync requires pair-array cloudstorage format, rejects object-shaped cloudstorage documents for apply, and does not fall back to a legacy one-shot path
• Dirty-stage and finalize calls each create backups for the files touched in that invocation

Quick start

To use steam-mcp, you need an MCP client that can launch a local stdio server. Build this repo, then point your client at the built server entrypoint.

Requirements

• Windows with a local Steam install
• Node.js >=24.15.0
• npm >=11.13.0

Build from source

npm install
npm run build

Connect it to an MCP client

Configure your MCP client to launch the built server over stdio.

{
  "mcpServers": {
    "steam": {
      "command": "node",
      "args": ["packages/steam-mcp/dist/index.js"],
      "cwd": "C:\\path\\to\\steam-mcp"
    }
  }
}

The exact config shape depends on the client, but the runtime entrypoint in this repo is packages/steam-mcp/dist/index.js after npm run build.

Guided workflows

If your MCP client supports prompts, steam-mcp includes built-in workflows for common tasks:

• steam_library_curator — safe library analysis, search, recommendations, exports, and links
• steam_wishlist_curator — read-only selected-user wishlist curation, sale/discount discovery, wishlist search, Deck shortlisting, exports, and links
• steam_collection_planner — plan-first collection or hidden-state changes with protected-collection awareness
• steam_deck_backlog_triage — shortlist Steam Deck-friendly backlog candidates
• steam_discovery_router — broad-intent discovery guidance that evaluates plausible discovery surfaces, then chooses one primary path and at most one adjacent fallback across the current validated Steam MCP discovery surface
• steam_recently_played — read-only workflow for inspecting recent play history for the selected Steam user
• steam_store_query — read-only authenticated official catalog discovery that preserves official defaults when optional filters are omitted, supports bounded include/exclude facet filtering, and offers opt-in facet enrichment
• steam_featured_scout — read-only marketing-backed workflow for scouting featured/editorial Steam store placements while preserving marketing ordering after enrichment, deduplication, and bounded filtering
• steam_release_scout — read-only workflow for upcoming or newly released Steam catalog scouting

Environment variables

Steam detection and runtime overrides

• STEAM_ID — pin the Steam user ID to use
• STEAM_INSTALL_DIR — override the Steam install directory
• STEAM_USERDATA_DIR — override the Steam userdata directory
• STEAM_MCP_STATE_DIR — override where MCP-owned plans, backups, logs, and metadata cache files are stored
• STEAM_STORE_TTL_DAYS — positive integer day count before persisted store metadata is treated as stale and refreshed on next access; defaults to 30
• STEAM_API_KEY — Steam Web API key used for authenticated official catalog access, official similarity prioritization, and owned-game fallback metadata

Safety and default collection behavior

• STEAM_ENABLE_COLLECTION_WRITES — enable steam_collection_apply when set to 1
• STEAM_ENABLE_WINDOWS_ORCHESTRATION — when set to 1 on Windows, best-effort launch Steam during MCP startup, close Steam before each apply call, ensure it is stopped, leave Steam closed after a successful dirty-only apply, and best-effort relaunch it only after a finalize apply or a failed apply if the wrapper stopped it
• STEAM_DEFAULT_READ_ONLY_COLLECTIONS — JSON array of collection names to preserve during planning and apply
• STEAM_DEFAULT_IGNORE_COLLECTIONS — JSON array of collection names excluded from similarity, search, and list filtering when the tool opts in

Default MCP-owned state lives under %LOCALAPPDATA%/steam-mcp/:

• plans/
• backups/
• logs/
• metadata/

Tools overview

Tool	Purpose
steam_status	Inspect the detected Steam install, user, backend, and write safety state
steam_library_list	Enumerate owned games with filters such as collections, favorites, play state, and Deck status
steam_library_search	Search the local library with deterministic match reasons
steam_store_search	Search the public Steam store without authenticated session reuse
steam_store_query	Query the authenticated official Steam catalog while preserving official defaults for omitted filters, with bounded type, locale, release-state, free-to-play, and human-readable include/exclude facet filters plus opt-in facet enrichment; requires a Steam Web API key
steam_featured_scout	Scout authenticated official Steam marketing placements for featured/editorial apps via GetItemsToFeature, with bounded limit, type, and locale guidance plus preserved marketing ordering after official enrichment, deduplication, and bounded filtering; requires a Steam Web API key
steam_release_scout	Read-only upcoming/recent release scouting via official catalog access plus public appdetails enrichment, with optional locale passthrough and bounded human-readable facet filters; requires a Steam Web API key
steam_recently_played	Read-only recently played game listing via the official Steam Web API; requires a Steam Web API key
steam_wishlist_on_sale	Read-only selected-user wishlist sale view derived from official wishlist data plus live public appdetails price_overview; requires a Steam Web API key, reports unknownPriceCount for items with unknown price state, and omits those items from items
steam_wishlist_details	Read-only selected-user wishlist items enriched with public appdetails metadata and optional existing Steam Deck status data; requires a Steam Web API key, and missingDetailsCount covers only the scanned slice after any limit
steam_wishlist_search	Search enriched selected-user wishlist items with deterministic library-search semantics, optional Deck status filtering, and public appdetails metadata; requires a Steam Web API key
steam_wishlist_deck_shortlist	Shortlist selected-user wishlist items for Steam Deck play using existing Deck status data plus deterministic query or seed ranking; requires a Steam Web API key, and query takes precedence when both query and seedAppIds are supplied
steam_wishlist_discount_summary	Summarize active selected-user wishlist discounts from fresh public appdetails price_overview, with counts that ignore the returned-item limit; requires a Steam Web API key
steam_find_similar	Rank similar library or store candidates with deterministic ranking by default and optional official store prioritization for scope="store" or scope="both"
steam_collection_plan	Create a durable preview plan for collection or hidden-state changes
steam_collection_apply	Apply a generated plan when writes are enabled; plain apply performs the dirty stage, finalize=true completes finalize, and optional Windows orchestration can close Steam around apply calls, leave Steam closed after a dirty-only apply, and best-effort relaunch after finalize or a failed apply when the wrapper stopped Steam
steam_export	Render library or plan data as JSON or Markdown
steam_link_generate	Generate store, community, library, and launch links

Notes and limitations

• This is a local stdio MCP server, not a hosted service
• The project is Windows-first and assumes a local Steam installation
• Steam store and Steam Deck data are used as read-only enrichment sources
• steam_store_query is read-only, requires STEAM_API_KEY, preserves official client defaults when optional filters are omitted, supports bounded human-readable include/exclude genre/category/tag filtering via authoritative cacheable store details, treats includeFacets as opt-in enrichment only, may still return fewer than the requested limit after bounded post-filtering, uses facetsAvailable=false when no facet payload could be attached for an otherwise valid item, and complements the unauthenticated public-store steam_store_search path
• steam_discovery_router is a prompt-only guidance surface over the existing validated tools; it evaluates plausible discovery surfaces, then chooses one primary path plus at most one adjacent fallback and does not add a new discovery tool or Steam endpoint contract
• steam_featured_scout is read-only, requires STEAM_API_KEY, uses authenticated official marketing placements from GetItemsToFeature plus official store metadata enrichment, preserves marketing ordering after enrichment, deduplication, and bounded filtering, and is for featured/editorial discovery rather than release scouting
• steam_release_scout is read-only and fails explicitly when no Steam Web API key is available
• steam_recently_played is read-only and fails explicitly when no Steam Web API key is available or no selected Steam user can be resolved
• steam_wishlist_on_sale is read-only, requires STEAM_API_KEY, derives sale state from live public appdetails price_overview, reports items with absent/incomplete/unavailable price metadata via unknownPriceCount, and omits those unknown-state items from items
• Wishlist extension tools are read-only, use official wishlist APIs only for selected-user identity/count/item membership, enrich via public appdetails, use existing deterministic search/ranking and Deck status seams, and do not call undocumented wishlist sale/filter/category endpoints or undocumented Deck badge endpoints
• steam_wishlist_details applies limit before enrichment, so missingDetailsCount only reflects the scanned wishlist slice, not the full selected-user wishlist
• steam_wishlist_deck_shortlist uses query in preference to seedAppIds when both are supplied in the same request
• steam_wishlist_discount_summary uses fresh public appdetails price metadata and applies limit only to returned items, not discount or price counts
• steam_find_similar defaults to deterministic ranking; mode="official" is opt-in, only works with scope="store" or scope="both", and fails explicitly when STEAM_API_KEY is unavailable or the selected user cannot be resolved to a SteamID64
• Collection changes should follow the plan-first flow: preview with steam_collection_plan, then apply only after explicit confirmation and with writes enabled
• Collection sync is explicitly limited to cloudstorage JSON files; it does not modify localconfig.vdf, LevelDB, sharedconfig.vdf, or undocumented Steam APIs
• steam_collection_apply uses a staged flow: omit finalize for the default dirty stage, then call again with finalize=true to complete finalize
• You can close Steam yourself and run the staged flow without orchestration
• When STEAM_ENABLE_WINDOWS_ORCHESTRATION=1 is enabled on Windows, steam-mcp may best-effort start Steam during MCP startup; for a dirty-only apply the wrapper closes Steam if needed and leaves it closed, and after a finalize apply or a failed apply it best-effort relaunches Steam only if the wrapper stopped it
• Restart is best-effort only and does not imply Steam cloud sync has completed
• Staged apply requires Steam to stay closed; requireSteamClosed=false is rejected

More docs

• docs/prompts/steam-mcp-agent-prompts.md

Development

If you're working on the repo:

npm run build
npm test
npm run typecheck
npm run clean