Steam MCP Server

by Grinv

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TypeScript

Remote

Compare two players' libraries

compare_players

Read-only

Find games two Steam players both own, with individual playtimes, to answer 'what can my friend and I both play?'

Instructions

Find games two players both own, with each one's playtime — 'what can my friend and I both play', 'do we have anything in common'. Checks each player's FULL library to find every shared game, unlike get_owned_games whose own list stops at 50 by playtime by default — but the returned list here is itself capped at the top 50 shared games by combined playtime (check returned vs shared_count). Requires STEAM_API_KEY and both profiles' game-details to be public — otherwise it returns found:false, which ALSO covers one player's library lookup failing transiently; read reason, which says which case it is and whether retrying is worth it. Omit steamid to compare against yourself (STEAM_ID).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`steamid`	No	17-digit SteamID64. Omit to use the STEAM_ID configured on the server. Convert a vanity/custom URL name with resolve_vanity_url first.
`other_steamid`	Yes	The other player's 17-digit SteamID64 to compare against. Convert a vanity/custom profile name with resolve_vanity_url first.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.14.0Sep 27, 2026

changedOutput schema / oneOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "found": {
-        "const": false,
-        "type": "boolean"
-      },
-      "reason": {
-        "type": "string"
-      }
-    },
-    "required": [
-      "found",
-      "reason"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "found": {
-        "const": true,
-        "type": "boolean"
-      },
-      "games": {
-        "items": {
-          "additionalProperties": false,
-          "properties": {
-            "appid": {
-              "type": "number"
-            },
-            "name": {
-              "anyOf": [
-                {
-                  "type": "string"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "playtime_hours_a": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "playtime_hours_b": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            }
-          },
-          "required": [
-            "name",
-            "playtime_hours_a",
-            "playtime_hours_b"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "returned": {
-        "type": "number"
-      },
-      "shared_count": {
-        "type": "number"
-      }
-    },
-    "required": [
-      "found",
-      "shared_count",
-      "returned",
-      "games"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "found": {
+        "const": false,
+        "type": "boolean"
+      },
+      "reason": {
+        "type": "string"
+      }
+    },
+    "required": [
+      "found",
+      "reason"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "found": {
+        "const": true,
+        "type": "boolean"
+      },
+      "games": {
+        "items": {
+          "additionalProperties": false,
+          "properties": {
+            "appid": {
+              "type": "number"
+            },
+            "name": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "playtime_hours_a": {
+              "type": [
+                "number",
+                "null"
+              ]
+            },
+            "playtime_hours_b": {
+              "type": [
+                "number",
+                "null"
+              ]
+            }
+          },
+          "required": [
+            "name",
+            "playtime_hours_a",
+            "playtime_hours_b"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "returned": {
+        "type": "number"
+      },
+      "shared_count": {
+        "type": "number"
+      }
+    },
+    "required": [
+      "found",
+      "shared_count",
+      "returned",
+      "games"
+    ],
+    "type": "object"
+  }
+]

Changed1 schema field changedv0.13.1Aug 17, 2026

changedInput schema / properties / other_steamid / description

Previous value: -"The other player's 17-digit SteamID64 to compare against."New value: +"The other player's 17-digit SteamID64 to compare against. Convert a vanity/custom profile name with resolve_vanity_url first."

Changed3 schema fields changedv0.12.1Jul 30, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

removedOutput schema / anyOf

Removed value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "found": {
-        "const": false,
-        "type": "boolean"
-      },
-      "reason": {
-        "type": "string"
-      }
-    },
-    "required": [
-      "found",
-      "reason"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "found": {
-        "const": true,
-        "type": "boolean"
-      },
-      "games": {
-        "items": {
-          "additionalProperties": false,
-          "properties": {
-            "appid": {
-              "type": "number"
-            },
-            "name": {
-              "anyOf": [
-                {
-                  "type": "string"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "playtime_hours_a": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "playtime_hours_b": {
-              "anyOf": [
-                {
-                  "type": "number"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            }
-          },
-          "required": [
-            "name",
-            "playtime_hours_a",
-            "playtime_hours_b"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "returned": {
-        "type": "number"
-      },
-      "shared_count": {
-        "type": "number"
-      }
-    },
-    "required": [
-      "found",
-      "shared_count",
-      "returned",
-      "games"
-    ],
-    "type": "object"
-  }
-]

addedOutput schema / oneOf

Added value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "found": {
+        "const": false,
+        "type": "boolean"
+      },
+      "reason": {
+        "type": "string"
+      }
+    },
+    "required": [
+      "found",
+      "reason"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "found": {
+        "const": true,
+        "type": "boolean"
+      },
+      "games": {
+        "items": {
+          "additionalProperties": false,
+          "properties": {
+            "appid": {
+              "type": "number"
+            },
+            "name": {
+              "anyOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ]
+            },
+            "playtime_hours_a": {
+              "anyOf": [
+                {
+                  "type": "number"
+                },
+                {
+                  "type": "null"
+                }
+              ]
+            },
+            "playtime_hours_b": {
+              "anyOf": [
+                {
+                  "type": "number"
+                },
+                {
+                  "type": "null"
+                }
+              ]
+            }
+          },
+          "required": [
+            "name",
+            "playtime_hours_a",
+            "playtime_hours_b"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "returned": {
+        "type": "number"
+      },
+      "shared_count": {
+        "type": "number"
+      }
+    },
+    "required": [
+      "found",
+      "shared_count",
+      "returned",
+      "games"
+    ],
+    "type": "object"
+  }
+]

Addedv0.10.2Jul 22, 2026
Removedv0.8.1Jul 18, 2026
Addedv0.8.0Jul 17, 2026

TDQS

A4.6/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare readOnlyHint=true and openWorldHint=true, so the safety profile is already covered. The description adds substantial behavioral context: the returned list caps at top 50 by combined playtime while shared_count shows the full total, the found:false ambiguity covering transient failures, and how to interpret reason to decide whether retrying is worthwhile. Slight deduction: it doesn't specify pagination or how to access beyond the cap, but the found:false/reason explanation is rich.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with the core purpose, then a targeted contrast with a sibling, then a compact but information-dense note about limitations and failure modes. Every sentence earns its place; no fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given an output schema exists and the annotations cover readability/safety, the description covers what an agent needs: what it returns, the cap caveat, failure modes, and prerequisites. It could mention how to access the full shared list beyond 50, but that's a minor gap for a tool whose returned list is explicitly capped and whose output schema likely includes shared_count.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and both parameters have descriptions including the 17-digit pattern and conversion advice. The description adds the key semantic that omitting steamid compares against the configured STEAM_ID, and reinforces how to convert vanity URL names via resolve_vanity_url. This goes beyond the schema's own parameter docs.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource: 'Find games two players both own, with each one's playtime.' It differentiates itself from get_owned_games by explicitly noting the 50-game limit difference. The description makes the tool's purpose immediately identifiable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use phrasing ('what can my friend and I both play', 'do we have anything in common'), contrasts with get_owned_games, and mentions requirements (STEAM_API_KEY, public profiles) plus the fallback behavior when conditions aren't met. It also says omitting steamid compares against yourself, giving clear usage routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.