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

The annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds useful context about the daily leaderboard being UTC-based and the existence of a free-play mode, but it does not disclose details like return format, ordering, or what happens when no day is provided.

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?

A single sentence with no filler. It front-loads the verb and resource, then adds the key modal distinctions without redundancy.

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 clear annotations and a small schema, the description covers the essential choices: game and mode. The only notable omission is guidance on the day parameter, but the schema's date pattern and optionality partially fill that gap.

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 0%, so the description must compensate. It maps 'free-play' and 'UTC daily' to the mode parameter and 'one game' to the required game parameter, but it does not explain the optional day parameter or how its absence is interpreted.

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 uses a specific verb ('Read') and a precise resource ('free-play or UTC daily leaderboard for one game'). It clearly distinguishes this tool from siblings like arcade_read_game or arcade_games by naming the leaderboard and its two modes.

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 description makes the tool's context clear: use it to fetch a leaderboard for a game in free-play or daily mode. It does not explicitly name alternatives or say when not to use it, but the purpose is specific enough that an agent can infer correct usage.

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