steam-api-reference

name	steam-api-reference
description	Search and retrieve Steam Web API and Steamworks SDK documentation. Returns endpoint signatures, parameter descriptions, and code examples. Use when the user needs to call a Steam API, wants to know available endpoints, or is integrating Steamworks SDK methods.
standards-version	1.10.0
drift-ignore	stale-counts

Steam API Reference

Trigger

Use this skill when the user:

• Asks how to call a specific Steam API endpoint
• Wants to know what Steam/Steamworks APIs are available
• Needs parameter details for a Steam Web API method
• Is integrating the Steamworks SDK (C++, C#, or other supported languages)
• Asks about authentication (API keys, session tickets, etc.)
• Is a modder looking for Workshop or UGC API documentation

Required Inputs

• Query: the API, interface, or method the user is looking for (e.g., "get player achievements", "ISteamUserStats", "leaderboard upload")

Workflow

1. Identify the relevant API interface. Steam Web APIs are organized into interfaces:

   Interface	Purpose
   ISteamApps	App metadata, version checks
   ISteamUser	Player identity, friends, bans
   ISteamUserStats	Achievements, stats, leaderboards
   IPlayerService	Owned games, playtime, badges
   ISteamNews	Game news feeds
   ISteamRemoteStorage	Workshop / UGC file details
   IPublishedFileService	Workshop queries (newer API)
   ISteamEconomy	In-game economy, trade
   ISteamMicroTxn	Microtransaction support
   ISteamWebAPIUtil	API key validation, server info

2. Fetch documentation. Use the WebFetch tool to retrieve the relevant doc page:

   https://partner.steamgames.com/doc/webapi/{InterfaceName}
   

   For SDK methods:

   https://partner.steamgames.com/doc/api/{InterfaceName}
   

3. If the interface is unknown, search for the method:

   • Use WebSearch: "Steam Web API {user's query} site:partner.steamgames.com"
   • Or fetch the supported API list:

     https://api.steampowered.com/ISteamWebAPIUtil/GetSupportedAPIList/v1/?key={apikey}
     

     This returns all available interfaces, methods, and parameters. No key needed for public methods.

4. Present the endpoint information:

   • URL pattern: https://api.steampowered.com/{Interface}/{Method}/{Version}/
   • HTTP method: GET or POST
   • Parameters: name, type, required/optional, description
   • Authentication: whether a Steam Web API key is required
   • Response format: key fields in the JSON response

5. Provide a code example in the language most relevant to the user's project. Default to curl if unclear:

   curl.exe "https://api.steampowered.com/ISteamUserStats/GetPlayerAchievements/v1/?appid=440&key=YOUR_KEY&steamid=76561198000000000"
   

Authentication Guide

• Public endpoints (store data, app list, current players): no key needed.
• User data endpoints (achievements, stats, owned games): require a Steam Web API key.
• Publisher endpoints (sales data, partner APIs): require publisher API key + IP allowlisting.
• Get a key: https://steamcommunity.com/dev/apikey

Users should store their API key in an environment variable (STEAM_API_KEY) and never commit it.

Common Endpoints Quick Reference

Method	URL	Key?
Get app list	ISteamApps/GetAppList/v2/	No
App details (store)	store.steampowered.com/api/appdetails?appids=X	No
Current players	ISteamUserStats/GetNumberOfCurrentPlayers/v1/?appid=X	No
Player achievements	ISteamUserStats/GetPlayerAchievements/v1/?appid=X&key=K&steamid=S	Yes
Global achievement %	ISteamUserStats/GetGlobalAchievementPercentagesForApp/v2/?gameid=X	No
User stats	ISteamUserStats/GetUserStatsForGame/v2/?appid=X&key=K&steamid=S	Yes
Owned games	IPlayerService/GetOwnedGames/v1/?key=K&steamid=S	Yes
News for app	ISteamNews/GetNewsForApp/v2/?appid=X	No

Example Interaction

User: "How do I get a list of achievements for my game from the Steam API?"

Agent:

1. Identifies ISteamUserStats/GetPlayerAchievements and GetGlobalAchievementPercentagesForApp
2. Provides endpoint URLs, parameters, and auth requirements
3. Shows a curl example and explains the response structure
4. Notes: "For per-player achievements you need the player's Steam ID and an API key. For global unlock percentages, no key is needed."

MCP Usage

The Steam MCP server provides 25 tools that call Steam APIs directly, eliminating the need for manual curl commands for common operations.

Available MCP Tools (25)

No API key required (10 tools):

Tool	Description
steam_getAppDetails({ appid, cc?, l? })	Store data: price, reviews, tags, platforms, system requirements
steam_searchApps({ query, cc?, l? })	Search the Steam store by name
steam_getPlayerCount({ appid })	Current concurrent player count
steam_getAchievementStats({ appid })	Global achievement unlock percentages
steam_getWorkshopItem({ publishedfileid })	Workshop item details (title, tags, subscribers)
steam_getReviews({ appid, filter?, language?, review_type?, purchase_type? })	User reviews with filters and pagination
steam_getPriceOverview({ appids, cc })	Batch price check for multiple apps in a region
steam_getAppReviewSummary({ appid })	Review score, totals, and positive percentage
steam_getRegionalPricing({ appid, countries })	Pricing breakdown across multiple countries
steam_getNewsForApp({ appid, count?, maxlength? })	Recent news and announcements

Requires STEAM_API_KEY environment variable (8 tools):

Tool	Description
steam_getPlayerSummary({ steamid })	Player profile: name, avatar, online status
steam_getOwnedGames({ steamid, include_played_free_games?, include_appinfo? })	Game library with playtime data
steam_queryWorkshop({ appid, search_text?, cursor?, numperpage?, query_type?, requiredtags? })	Search and browse Workshop items
steam_getLeaderboardEntries({ appid, leaderboardid, rangestart?, rangeend?, datarequest?, steamid? })	Leaderboard scores and rankings
steam_resolveVanityURL({ vanityurl, url_type? })	Convert vanity URL to 64-bit Steam ID
steam_getSchemaForGame({ appid })	Achievement/stat schema with display names, descriptions, icons
steam_getPlayerAchievements({ steamid, appid })	Per-player achievement unlock status and timestamps
steam_getLeaderboardsForGame({ appid })	List all leaderboards with numeric IDs

SDK guidance / publisher key (7 tools):

Tool	Auth	Description
steam_createLobby({ type, max_members, metadata })	SDK guide	ISteamMatchmaking lobby creation code examples
steam_uploadWorkshopItem({ appid, title, ... })	SDK guide	ISteamUGC Workshop upload code examples
steam_updateWorkshopItem({ publishedfileid, ... })	Publisher key	Update Workshop item metadata via partner API
steam_setAchievement({ steamid, appid, achievement })	Publisher key	Unlock an achievement (dev/test)
steam_clearAchievement({ steamid, appid, achievement })	Publisher key	Re-lock an achievement (dev/test)
steam_uploadLeaderboardScore({ appid, leaderboardid, ... })	Publisher key	Upload leaderboard scores
steam_grantInventoryItem({ appid, steamid, itemdefid })	Publisher key	Grant inventory items

When an MCP tool exists for a given endpoint, prefer it over raw curl calls. For endpoints not covered by MCP tools (user stats, microtransactions), continue using the Web API directly.

The Steamworks SDK documentation and example generation logic remain the same regardless of MCP availability.

Common Pitfalls

1. Confusing Web API and Steamworks SDK endpoints — the Web API (HTTP) and SDK (in-process C++) have overlapping functionality but different auth models. Web API uses API keys; SDK uses the logged-in Steam user.
2. Using the public API base for partner endpoints — api.steampowered.com vs partner.steam-api.com. Partner endpoints require IP allowlisting and won't work from the public base.
3. Not checking API rate limits — Steam rate-limits most endpoints to ~100K calls/day per key. Exceeding this results in HTTP 429 errors with no warning.
4. Ignoring the format parameter — some older endpoints default to VDF output instead of JSON. Always pass format=json for programmatic consumption.

See Also

• Steam Store Lookup - look up game store data using the APIs documented here
• Steam Player Stats - query player data using ISteamUserStats and IPlayerService endpoints