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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the data-eligibility rule (revealed, non-practice rounds only) and the fact that no money/stakes are involved, which matters for an agent choosing between this and arena_stake or arena_pnl.

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?

Two sentences, front-loaded with the subject ('Task leagues'), and the parenthetical list efficiently packs the return contents without filler. Every clause carries 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?

Low complexity (one optional param, no nested objects, no output schema), so the description carries the return-value burden and does so by enumerating the badge/spotlight artifacts. The only gap is the cross-league behavior when 'league' is omitted.

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 description coverage is 100%, and the single optional 'league' parameter is documented in the schema, so the baseline is 3. The description adds nothing about the parameter's semantics, notably what happens when 'league' is omitted (all leagues aggregated?).

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 resource, 'shareable rank badges and the top-bot spotlight,' and enumerates the concrete artifacts returned (top bot, ranked bots, share text, README badge Markdown). It is clear what the tool produces, but it never distinguishes itself from the very similar sibling arena_leaderboard, so an agent must guess which ranking tool to pick.

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 scope constraints ('Ranks only from revealed non-practice rounds', 'No stakes, no money') imply the situations where this applies and implicitly rule out the staking/pnl tools. There is no explicit when-to-use instruction and no named alternative, so selection guidance vs arena_leaderboard or arena_leagues is left to inference.

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