List Legal Chess Moves

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description doesn't need to restate these. The description adds behavioral context by listing the output fields (SAN, UCI, piece, capture, promotion), which informs the agent about the nature of the response. No contradictions with annotations are present.

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, front-loaded sentence that clearly states the action and output fields. It contains no filler or redundant information, making it highly concise and well-structured.

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?

Given the tool's simplicity (one parameter, no nested objects) and the presence of an output schema, the description adequately covers the necessary context. It specifies the output fields and the operation's scope ('current position'). It could have mentioned edge cases (e.g., no legal moves) or the meaning of 'current position' in terms of move history, but these are not critical for a basic move-listing tool.

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?

The input schema has one parameter, game_id, with no description coverage (0%). The tool description does not mention game_id at all, leaving its semantics implicit. While the parameter is self-explanatory (identifying the game), the description fails to compensate for the lack of schema descriptions, providing no added meaning beyond the name and type.

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 clearly states the tool lists all legal moves in the current position, specifying the output fields (SAN, UCI, piece, capture, promotion). This distinguishes it from sibling tools like game_play_move (which executes moves) and move_candidates (which may provide candidate analysis), making the purpose unambiguous.

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?

The description implies usage is for retrieving legal moves for the current game identified by game_id, but it does not explicitly contrast with alternatives like move_candidates or position_analyze. The context is clear, but no exclusions or specific when-to-use guidance are given, so a 4 is appropriate.

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