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 meaningful behavioral context beyond annotations: it reveals the Glicko-2 ranking system, the concept of a belt holder, and the important nuance that house players appear unranked at fixed ratings.

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 two short sentences with no wasted words. The core identity is front-loaded, and the second sentence provides a specific behavioral detail that 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?

For a simple read-only tool with one optional enum parameter, this is nearly complete: it explains what the leaderboard is and a special ranking rule. The main gaps are the lack of an output schema or any description of the returned shape, and 'belt holder' is mentioned but never defined, though these are minor for invoking the tool correctly.

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?

With schema description coverage at 0%, the description needed to compensate for the 'game' parameter, but it only says 'for a game' and never mentions the parameter or the valid value 'chess.' The enum in the schema does the actual semantic work, so the description adds little value for parameter understanding.

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 identifies the resource as a 'Ladder (Glicko-2) and belt holder for a game,' making it clear this is the leaderboard/ranking view rather than a game-action tool. It does not contain a specific verb like 'get' or 'list,' so it falls short of the 5-level specificity, but it is otherwise unambiguous and self-differentiating among the siblings.

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?

There is no guidance about when to use this tool versus alternatives such as match_state, queue, or list_callouts. The description implies its role as a leaderboard but never states conditions, exclusions, or related tools, leaving usage entirely to inference.

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