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

Annotations indicate readOnlyHint=true, and the description adds that windows anchor to latest sale date and that median_usd is a mixed-grade reference, preventing misinterpretation. No contradictions.

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?

Three sentences with clear structure, no fluff. First sentence covers purpose and filters, second window behavior, third clarifies data usage.

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?

Given output schema exists, the description covers all needed: filters, window anchoring, max limit, and provides warning on median_usd use. No missing critical information.

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 covers all parameters with enums and descriptions. The description adds context: window anchoring, the meaning of PSA10, and the mixed-grade caveat for median_usd beyond schema.

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 states 'Most-traded graded Pokémon cards by verified sales count over a 24h / 7d / 30d window', which clearly defines the verb (list leaders) and resource (traded cards). It distinguishes from siblings like card_price and market_movers by focusing on volume and verified sales count.

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 specifies filters (language, grade_company) and explains window anchoring behavior. It also advises using card_price for precise per-grade quotes, providing an alternative. However, it doesn't explicitly exclude other tools like market_movers or recent_sales.

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