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

With no annotations provided, the description carries the full burden. It discloses key behaviors: it outputs SAN moves with per-ply evals and re-searches after each ply. It does not mention side effects or authentication needs, but the behavior is clearly described for a read-like operation.

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 sentence of 19 words that immediately conveys the tool's purpose and key details. It is appropriately concise and front-loaded with the main action.

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 description lacks explanation of the output format (how are SAN moves and evals returned?) and does not cover the behavior for different parameter values. Given no output schema and three parameters, the description is incomplete for selecting and invoking the tool correctly.

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 description does not explain any of the three parameters (fen, depth, maxPlies) despite having 0% schema coverage. It adds no meaning beyond what the schema provides, leaving the agent without guidance on how to set these parameters.

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 plays out Stockfish's predicted principal variation as SAN moves with per-ply eval and re-searches after each ply. This specific verb-resource combination distinguishes it from the sibling sibling 'evaluate_position', which likely provides a static evaluation rather than a sequence of moves.

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 for obtaining a line of best play, but it does not explicitly state when to use this tool versus 'evaluate_position' or provide any exclusions or context. The guidance is implicit rather than explicit.

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