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

Annotations already establish the safe read-only, idempotent profile, and the description goes well beyond them: result ordering (most-played first), the fields returned (matches, last match, rank), the null-rank boundary outside the top 100–150, and the 1-credit cost. Cost disclosure in particular is behavioral information no annotation carries.

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?

Front-loaded with the primary purpose and packed densely with no filler; nearly every clause carries information. The tour/league sentence is the weakest part, reading as slightly tangled and introducing a 'tour' concept absent from the schema.

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 an output schema present, return values need not be spelled out, and the description still summarizes them, plus defaults and cost. The one gap is the mismatch between the described 'tour: atp (default) or wta' and the schema, which exposes only a 'league' enum of tennis/wta — an agent may be unsure how to express 'atp'.

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%, so baseline is 3, but the description adds real semantics: accents are optional in names, country codes are three-letter (e.g. ITA), and it attempts to explain how the tour setting relates to the league parameter on the shared endpoint. The extra context outweighs the schema's own field descriptions.

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 specific verb and goal ('Use to find a player's id') and names the two searchable dimensions (name, country code). This clearly separates it from get_player, which takes an id the agent presumably already has.

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 phrase 'Use to find a player's id' implies the lookup-then-fetch workflow and steers toward the id-based sibling without naming it. Tour/league selection guidance is given, but there is no explicit exclusion telling the agent when not to search (e.g. when the id is already known).

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