Get a player's achievements

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

Annotations already declare readOnlyHint and openWorldHint. The description adds behavior beyond annotations: the 'achievements' array is capped at 200 (unlocked first), and users should check 'returned' vs 'total'. It also clarifies that 'found:false' can result from either an invisible profile or a game with no achievements. This is valuable context that annotations alone don't provide.

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

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

The description is a single paragraph but front-loaded with the core purpose. It is reasonably concise given the amount of important detail it packs (limits, error cases, prerequisites, sibling differentiation). While a bit dense, every sentence adds value. Could benefit from slight structuring (e.g., bullet points for constraints) but still effective.

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

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

The tool has 3 parameters (one required), an output schema (present but not shown), and moderate complexity. The description covers key contextual elements: data fields, per-achievement limit, error conditions, and prerequisites. It does not explain the output schema (unnecessary as output schema exists) but includes enough to use the tool effectively. Minor gap: no mention of rate limits or pagination for large achievement lists.

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

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

Schema has 100% coverage, so baseline is 3. The description adds semantic value: 'appid' from search_games, 'steamid' can be omitted to use configured STEAM_ID, convert vanity URL with resolve_vanity_url, 'language' overrides STEAM_LANGUAGE. These details help the agent use parameters correctly beyond the schema descriptions.

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

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

The description starts with a specific verb and resource ('Get a player's achievement progress for one game') and lists exact data returned (unlocked count, % complete, per-achievement unlock dates). It distinguishes from sibling tools 'get_game_achievements' and 'get_global_achievements' by specifying their different purposes, achieving high differentiation.

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

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

Explicitly states when to use this tool ('get a player's achievement progress') and when to use alternatives ('For the full achievement list... use get_game_achievements; for rarity... use get_global_achievements'). Also provides prerequisites (STEAM_API_KEY, public profile with game-details visibility) and explains the 'found:false' return meaning. This covers both when-to-use and when-not-to-use.

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