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

Annotations already mark this as read-only and idempotent, and the description adds valuable behavioral context beyond them: the $0.005 USDC x402 payment requirement, the unpaid-call challenge behavior, the no-data/no-cost guarantee, and the null pseudonym behavior. It also discloses the equivalent HTTP route. No contradiction with annotations.

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 dense but every sentence earns its place: scope and return fields, use case, null handling, payment and failure semantics, and HTTP route. The core purpose is front-loaded, and nothing is redundant.

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 compensates by listing the returned fields. It fully explains invocation-relevant side effects such as payment, unpaid responses, and the no-data/no-cost rule. For a 3-parameter optional-parameter read-only tool with full schema coverage, this description 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?

The schema already provides 100% coverage with descriptions, defaults, and examples for all three parameters: limit, metric, and window. The description's mention of 'volume or realised profit' and '1d, 7d, 30d or all-time' does not add meaning beyond what the schema already states, so the baseline of 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?

The description clearly identifies the resource (Polymarket trader leaderboard), the core sorting metrics (traded volume or realised profit), the available windows, and the returned fields. It distinguishes this tool from siblings like polymarket_trades or polymarket_markets by focusing specifically on leaderboard rankings rather than market or trade data.

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 gives a clear use case: 'Use it to find who is moving size on the venue.' It does not explicitly name alternative tools or state when not to use it, but the context is strong enough that an agent can infer when this leaderboard is the appropriate choice.

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