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

Annotations already cover read-only, idempotent, non-destructive. The description adds genuinely new behavioral facts: results are ordered newest-first, there is a 5-credit cost, and default tour is atp. That is meaningful context beyond the structured fields, though it says nothing about pagination or result-size limits.

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?

Three dense sentences: purpose and returned fields first, then filters, then tour/league and cost. Every clause carries information and nothing is repeated from the schema verbatim.

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?

Output schema exists and the description still summarizes payload shape, and it covers cost and tour defaults. The gap is the undocumented pagination behavior and the unresolved tour-vs-league naming, which leaves the agent with a slightly ambiguous call signature.

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 67% and the description does explain filters in natural terms (season, surface, opponent_id, tournament_id, draw) and clarifies the league='wta' case. However it introduces a 'tour: atp (default) or wta' option that does not exist in the schema (only 'league' does), which risks an agent passing an invalid parameter, and it never mentions limit/offset.

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/resource ('a player's matches') and enumerates the returned fields (tournament, surface, round, opponent, result, score by set, rating before/after), which makes it distinguishable from get_matches and get_head_to_head. It never explicitly names a sibling though, so the agent must infer the distinction from the player-scoping.

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 clear context for use (per-player match history, newest first) and lists the available filtering dimensions plus the tour/league default behavior. It does not say when to prefer get_matches, get_head_to_head, or get_player_stats instead, so the alternative-routing element is missing.

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