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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful context the annotations do not carry: the 7-day window, that prices are used-market, and that both decreases and increases are returned. It stops short of saying how many movers come back, whether they are ranked, or how they are scoped to a market.

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 eight-word sentence with the time window and both movement directions front-loaded. Nothing is wasted, and there is no filler to remove.

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 parameterless read with no output schema, the description should still indicate roughly what comes back (e.g. a ranked list of N models with percentage change). It conveys the concept but leaves result size, ordering, and market scope unspecified, which an agent needs to know to trust the output.

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 tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. The description correctly implies a no-argument call, though it could have noted that the result size is fixed and uncontrollable.

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?

Names a concrete resource: the top 7-day movers in used prices, in both directions (drops and rises). An agent can tell this is a leaderboard rather than a per-model price lookup, but nothing states how it differs from get_price_history, which could plausibly surface the same movement 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?

There is no when-to-use guidance, no mention of alternatives such as get_price_history, and no exclusions. The agent must infer the use case purely from the phrase 'biggest 7-day drops and rises'.

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