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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower; the description adds genuinely non-redundant traits: a 25-second execution deadline, the disclaimer that it produces a statistical profile rather than a verdict, and accepted move encodings. It omits failure behavior (e.g., what happens on timeout) but adds real value beyond the annotations.

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?

Four compact sentences, front-loaded with the core action and metrics before the qualifiers. No filler, though the first sentence is dense and packs metric definitions alongside the operation.

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?

With no output schema, the description correctly names the return shape (statistical profile with per-position metrics) and flags the time budget. The main remaining gap is the undocumented depth control, but for the essential call path the description is sufficient.

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 0% and there are 2 parameters, so the description must compensate. It partially does for the move format ('Accept SAN or UCI moves') and implies the positions input, but the depth parameter (range 4–20, default 12) and the FEN field format are entirely undocumented in both schema and description.

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 gives a specific verb (compare) and resource (supplied chess positions and played moves), names the engine (Stockfish UCI), and states the exact metrics computed: first-choice agreement and centipawn loss per position. An agent knows precisely what this does, and no sibling tool overlaps with the chess domain.

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?

It supplies clear context — accepted move formats (SAN or UCI), the output nature (statistical profile, never a cheating verdict), and an operational bound (25-second deadline). It stops short of explicit when-not-to-use guidance or naming an alternative, but no sibling is a plausible substitute, so little is left ambiguous.

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