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

Annotations already establish readOnlyHint=true and openWorldHint=false, and the description adds useful non-schema context: the weekly eligibility rule, prize amounts, and the fact that payouts are manual and sponsor-reviewed. It does not disclose return format or any rate-limit concerns, but it meaningfully supplements the safety profile already given.

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 compact and front-loads the free/daily default before explaining the weekly variant and rewards. Every sentence carries relevant information, though the dense em-dash construction slightly reduces readability.

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 leaderboard with three optional parameters and no output schema, the description covers default behavior, weekly mode, eligibility criteria, and prize context. It could mention the shape of the returned leaderboard data, but the core invocation guidance is complete.

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%, so the parameter meanings are already fully documented. The description adds the default-mode behavior and weekly eligibility context, but it does not add syntax or format detail beyond what the schema provides; a baseline score 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?

The description clearly identifies the resource as an arena leaderboard and distinguishes its default daily mode from the weekly mode. It does not explicitly contrast itself with the sibling arena_current_round, so it falls short of full sibling differentiation.

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?

It states the default behavior (current daily round) and the exact switch to use for the weekly board (weekly=true, optional week=Monday YYYY-MM-DD). It does not name alternatives such as arena_current_round or explain when not to use this tool, so it is clear but not exhaustive.

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