One game with moves and evals

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description still adds real behavioral context: evals and judgments are only present 'when Lichess has analysed the game', and the PGN is 'clean' (headers + moves, no comments). That conditional availability is exactly the kind of nuance annotations cannot express.

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?

Two sentences, zero preamble, with the resource and payload front-loaded before the conditional eval caveat. The enumeration is long but each item is substantive rather than filler; slightly list-heavy for a description that could group related fields.

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?

An output schema exists, so return values need no further explanation, and the description nonetheless sketches the payload shape. Combined with full schema coverage and clear annotations, an agent has everything needed to invoke it; only the routing versus sibling list tools is left implicit.

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 description coverage is 100%, so both parameters (game_id format/URL, include_pgn default) are already fully documented in the schema. The description mentions 'Includes clean PGN' and 'every move in SAN', which aligns with but does not extend the schema semantics. Baseline 3 applies.

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?

States a specific verb ('Fetch') plus a precise resource ('one Lichess game') and enumerates the returned payload: players, ratings, result, opening, time control, SAN moves with clock times, engine evals/judgments, and PGN. The singular 'one game' clearly separates it from sibling recent_games (a list) and get_player (a player entity).

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?

Usage is implied by the payload description, and the clause 'when Lichess has analysed the game' signals a conditional expectation the caller should have. However, no sibling is named and no when-to-use/when-not guidance is given, so the agent must infer that recent_games is the path for discovery and this tool for a known game_id.

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