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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds real behavioral context beyond them: the price basis (PSA 10 where available, raw otherwise), what the percentage is measured against, and the 300% data-quality cutoff that silently removes rows. It does not explain result ordering beyond 'biggest' or any paging behavior, keeping it out of 5 territory.

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, front-loaded with the trigger, then output semantics, then exclusions. No filler and no repetition of the title.

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?

An output schema exists, so return-shape detail is unnecessary. What an agent still needs -- when to call it, what the numbers mean, what is filtered out, and when to look elsewhere -- is all present.

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 coverage is 75% and already documents game, direction and min_market_usd separately. The description adds meaning the schema does not: the rank metric is PSA 10 when present and raw otherwise, which is what ties min_market_usd's raw-price filter and the 'biggest gainers' ordering together.

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?

States a specific resource (cards), a specific qualification (30-day price movers), and the exact user intents it serves (rising, hot, spiking, crashing, trending). It is clearly distinguishable from siblings like get_price_history and liquid_movers without opening either schema.

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?

Gives explicit trigger conditions plus two exclusions ('Do not use for a single named card or for long-term history'), which is stronger than most definitions. It stops short of naming the sibling tool to use instead in those cases, so it is not a full 5.

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