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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is free to add analytical context — and it does: a minimum sample threshold ('at least 5,000 modelled shots'), tournament coverage limits ('ATP only'), a significance bar (p < 0.01), and an honesty caveat ('A weak habit, not a proven gain'). These are the things an agent cannot get from annotations or schema.

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?

There is almost no wasted content — every clause defines a board — but the entire payload is delivered as one unbroken em-dash-separated block, so an agent must read linearly to find the definition of a single value. Front-loading the purpose is good; the parameter dictionary would be far more scannable as a list.

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 carries the burden of explaining return values, and 'Top 10 ... players on one tactical measure' reasonably implies a ranked ten-row result. It never names the returned fields (rank/player/value) or their units, which is the main remaining gap for a read-only leaderboard endpoint.

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 coverage is 100% with all three parameters enumerated and labelled, so the baseline is 3; the description exceeds it by unpacking each of the ten board values with its underlying metric ('per 100 shots, opponent-adjusted', 'usage-weighted gap per 100 first serves', rally-relative execution). Tour and scope are left to the schema, which already documents them adequately.

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?

Opens with a concrete verb-and-resource statement: 'Top 10 ATP or WTA players on one tactical measure,' which tells an agent exactly what comes back. It does not differentiate itself from siblings (explain_match, get_game_plan, get_player), but the purpose itself is unmistakable.

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 rather than stated: an agent can infer this is for leaderboard ranking, and the per-board notes embeds one genuinely useful constraint (long_rallies_hold_up / long_rallies_fade are 'ATP only'), which prevents an invalid tour+board combination. There is no explicit when-to-use-vs-alternative guidance and no routing to the sibling tools.

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