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

Goes well beyond the annotations: discloses a 5-minute result cache, warns that the current bid may be stale and should be treated as a lower bound near close, and notes bidder names are masked by the site. Those are exactly the freshness and data-shape caveats an agent needs before quoting a price.

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 what the tool returns, then id provenance, then the staleness caveat. Nothing is redundant with the schema and no sentence could be dropped without losing an operational fact.

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 compensates by enumerating the returned fields, and it closes the remaining gaps (id source, cache staleness, masked bidders, upstream API). An agent has everything needed to call it and to interpret the result responsibly.

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?

Single parameter with 100% schema coverage, so the schema already defines item_id with an example. The description adds value by describing the id's provenance (it must come from a sibling search tool), which the schema does not say, though it adds no format or range detail.

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 verb+resource+scope: "Full detail for one ShopGoodwill auction lot by item id," then enumerates exactly what comes back (bid history, buy-now, seller, shipping, images, end time). It is clearly separable from shopgoodwill_search and shopgoodwill_sold_search, which the description itself names as the id sources.

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?

Explicitly tells the agent where item ids must come from (shopgoodwill_search / shopgoodwill_sold_search) and gives a concrete operating rule for near-auction-close use. It stops short of a when-not-to-use statement or a named alternative for other lookup patterns, so it lands just under a 5.

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