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

Annotations already mark readOnlyHint, openWorldHint, and destructiveHint. The description adds useful context: 'Parallel-safe: yes', 'Upstream cost: 1', an eligibility threshold (50 break opportunities), and default season/tour behavior. The phrase 'read return-side' is ambiguous, and there is no mention of pagination or output size limits beyond schema defaults, so a 5 is not warranted.

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?

The purpose is front-loaded and sections are clearly labeled, but the main sentence is duplicated verbatim in the When-to-use section. Some phrasing like 'read return-side' is awkward and the bullet 'season tables; clutch/serve-efficiency leader queries' adds little. It could be tightened without losing information.

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?

Covers the eligibility threshold, tennis-only scope, optional tour, season default, and parallelism. The presence of an output schema relieves the need to document return values. Minor gaps remain: game selection guidance is left to the schema enum, and 'read return-side' is unclear. Overall, the definition provides enough for correct invocation.

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?

The schema covers all 5 parameters at 100% with descriptions, examples, defaults, and an enum for game. The description adds the 'omit tour for the combined board' nuance and repeats the season default, but it does not materially expand on parameter meanings. Baseline 3 is appropriate given the high schema coverage.

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 a specific metric (share of break opportunities converted) with a clear resource (tennis season leaderboard) and ordering (highest pct first). It is distinct from the sibling leaderboard_break_points_saved because it focuses on conversion rather than saves. The tennis-only scope and season default further pin down intent.

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?

Explicit 'When to use' section lists use cases and a 'Do not use when' section names specific sibling tools (standings, rankings_movers, player_form) with conditions. It even suggests preferring this over call_api for agent-normalized rows. An agent needs no inference to decide when to invoke it.

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