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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds meaningful behavior beyond that: both modes of operation, the tiebreak cascade used to rank standings, and the fact that play happens through a separate tool rather than here.

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?

Front-loaded with the tournament concept, then the two modes in quick succession; every sentence carries information. It is a dense paragraph rather than structured bullets, and the closing sentence about the play tool is useful but could be trimmed.

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?

With no output schema, the description carries the burden of describing returns and does so thoroughly for both modes, including the exact ranking tiebreakers. Minor omissions (how many Cups are listed, whether recent Cups are bounded) keep it short of full completeness.

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% and there is only one parameter, whose description already explains the id format and the omit-to-list behavior. The description restates the same semantics ('With no cup_id it lists... With cup_id it returns that Cup') rather than adding format, validation, or edge-case detail, so the baseline 3 is appropriate.

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?

Names a concrete verb-and-resource pair and splits the behavior cleanly into two modes: list Cups without cup_id, retrieve one Cup with cup_id. The description goes on to enumerate the exact return contents (standings, tiebreak order, pairings, results, champion), so an agent knows precisely what it gets without opening the schema.

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 with/without cup_id selection rule is stated explicitly, which is effectively the when-to-use condition for this tool. It also points to the 'one-call play tool' for the actual game action, routing the agent away from misusing this read-only tool. It does not, however, contrast itself against near neighbors like pit_leaderboard or pit_match_state.

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