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

No annotations are provided, so the description carries the burden and does disclose that the call is read-only, free, and sourced only from the operator's own shop (a meaningful data-coverage caveat). It does not mention rate limits, failure modes, or how sparse the sample may be when the shop has no matching sales.

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 short sentences, zero filler, front-loaded with the use case and the return payload before the sibling comparison. Every clause carries selection-relevant information.

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 usefully summarizes the return shape (median/low/high sold prices) and the data source. Only minor gaps remain: no note on result sparsity or what happens when the item has no sold history in the operator's shop.

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?

Only one parameter exists and its schema description coverage is 100%, so the schema already defines 'q'. The description implies the query is an item but adds no syntax, matching, or formatting detail beyond that, which is baseline-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?

States a specific resource ('real completed transactions') and a concrete return payload ('median/low/high sold prices'), scoped to the operator's own eBay shop. It also explicitly separates itself from sibling get_worth, so an agent can pick it apart from alternatives without reading the 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 an explicit selection rule: prefer this for actual sold comparables, use get_worth for live asking-price estimates. That is a when/when-not pair anchored to a named sibling rather than implied context.

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