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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds meaningful context beyond them: the exact payload contents (price, bids, condition, photos, bidders, seller) and the flat 5-point cost per successful run, which an agent cannot infer from structured fields.

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?

One front-loaded sentence packs scope, input forms, return contents and cost with no filler. The long comma-separated field list is dense but each item is informative, so little is wasted.

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 annotations covering safety, a single fully documented parameter, and no output schema, the description closes the main gap by enumerating the returned fields and stating the cost. Only the routing to sibling tools is left implicit.

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 100% and the schema itself supplies the example id, so the baseline applies. The description's 'by auction id or URL' merely restates the parameter's dual acceptance without adding format or validation detail beyond the schema.

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 and resource ('Get one live or completed Yahoo! Auctions Japan listing'), names the two accepted identifier forms (auction id or URL), and enumerates the returned data. It is clearly distinguishable from sibling search/list tools.

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?

The description implies a single-record lookup by id or URL and notes that both live and completed listings are covered, but it never names the obvious alternatives (run_yahoo_auctions_items_search for discovery, run_yahoo_auctions_items_closed_search) or states when to prefer them.

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