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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the payload contents (matches, top bots, records), which tells the agent what a call yields beyond the annotations. It adds no cost/latency/pagination context, keeping it at 4.

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 trigger condition and alternatives in two compact clauses plus a worked example. Minor waste in leading with the tool name restated as the title, but otherwise every sentence earns its place.

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?

An output schema exists, so return-value explanation is unnecessary, and annotations cover safety; what remains is knowing which game scope and format to pass, which the example supplies. Nothing essential is missing 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?

Schema coverage is 100%, so the baseline is 3; the description exceeds that by giving a concrete call example with a realistic game id ("asteroid_dodge"), conveying identifier format that the schema does not. It says nothing about the optional `key` parameter, so it is not a 5.

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 and scope: "one game's meta card (matches, top bots, records)", and explicitly names two siblings it is not (stats_leaderboard, arena_leaderboard). It does not differentiate from stats_overview or stats_bot, which are also aggregate-stats tools, so it falls short of a 5.

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?

A "WHEN:" clause states the trigger condition, and the alternatives are named with their distinguishing nature (Elo list vs live scores). No explicit when-not or prerequisite (e.g. auth requirement) is given, but the routing guidance is clear.

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