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

Beyond the annotations (readOnlyHint=true, destructiveHint=false), the description discloses that it is parallel-safe and the upstream cost is 1. It also adds specifics like the minimum 10 tiebreaks to qualify and the default season (2026). These are useful context not covered by 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?

The description is well-structured and front-loaded with the core purpose, followed by usage conditions, exclusions, and constraints. Every sentence adds value: the do-not-use section preempts misrouting, and the qualification rule is concise.

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?

Given that the tool has an output schema (not shown) and annotations covering safety, the description is nearly complete. It covers usage, exclusions, defaults, and a qualification rule. Minor gap: it does not specify the return format or pagination beyond 'limit', but with an output schema, that is acceptable.

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 has 100% coverage, so the baseline is 3. The description adds key semantics: the 'tour' parameter is optional and maps to the combined board when omitted, and the 'division' parameter is a synonym for tour, clarifying its usage. It also confirms 'game' is tennis-only, which is not fully explicit in the enum alone.

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?

The description clearly states the tool computes the share of classic 7-point tiebreaks won per player for tennis, ordered by highest percentage. It includes a specific verb ('share'), resource ('tiebreak-win-pct leaderboard'), and scope, with an example output context. It also mentions real match-set aggregatesaving for clarity.

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 description explicitly lists when to use (clutch/serve-efficiency leader queries), what to prefer over (raw leaderboard via call_api), and do-not-use cases for related rankings (standings with game tennis, rankings_movers, player_form). It also specifies tennis-only and the season/tour defaults.

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