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

Annotations already declare readOnlyHint and closed-world, so the description correctly focuses on value-add: it is free, consumes no search quota, and the duty field is conditional ("where known"), warning the agent that output may be partial. It omits what happens with zero matches or how categories are matched.

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?

Two dense sentences: the first front-loads the returned metrics, the second carries the cost and quota caveat. Nothing is redundant or padded.

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 and no annotation coverage of returns, the description does the work of naming the returned statistics and the conditional duty field. Currency, units, and minimum sample size for a meaningful band are unaddressed but are secondary for a lookup tool.

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 single parameter has 0% schema description coverage, so the description must carry the burden; "for a product" and "matching fair categories" hints that query is a product term matched against categories. It does not specify expected format (SKU vs. keyword), which is a real gap for the only required input.

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 the resource (price statistics for a product) and enumerates the specific outputs: median, middle half, median MOQ, and US import duty. This is clearly distinct from search_listings or get_exhibitors, though it does not name a sibling explicitly.

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?

"Free; does not spend a search" implies this is the cheap alternative to a full listing search, which is real usage signal. However, it never states when to prefer this over search_listings or what happens when no priced listings match, leaving the selection decision partly to inference.

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