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

Annotations already carry readOnly/idempotent/non-destructive, so the description's added value is the credit cost (2 credits) and the data-coverage caveat (weekly lists hold roughly the top 100-150 for most weeks since 2007), which materially shapes expectations. No contradiction with 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 tight sentences, front-loaded with the primary use case and each subsequent sentence handling a distinct concern (alternate mode, coverage, league, cost). No filler.

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?

An output schema exists, so return values need no explanation; the description covers modes, coverage, league switching, and cost. The only gap is the phantom 'tour' parameter reference, which an agent must reconcile against the schema's league enum on its own.

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 the baseline is 3; the description earns an extra point by explaining how season and week combine, that date yields the list in force, and how tour maps onto the league enum. The reference to 'Tour: atp (default) or wta' names a parameter that does not exist in the schema, which slightly muddies the league semantics.

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?

States the resource (ranking list) and its three modes of resolution (latest default, season+week, date), plus the fields returned (rank, previous rank, points, player). It also separates the single-player history mode, so the agent can tell it apart from the list mode, though it never contrasts itself with the sibling get_ratings, which is the most likely confusion point.

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?

Gives concrete routing rules: use the list form by default, pass player_id 'instead' for one player's history, and pass league: "wta" for WTA on the shared endpoint. Missing only an explicit statement of when to prefer a sibling such as get_ratings or get_player_stats.

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