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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so the safety profile is covered. The description adds a genuinely non-obvious trait: '1 point per returned record,' a cost/billing disclosure that matters for how many items the agent requests.

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 dense sentence with the resource and modality front-loaded, followed by the filter enumeration. The filter list is long but each item earns its place by signaling available dimensions.

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 23-parameter, zero-required search tool with no output schema, the description covers inputs and adds a cost note, but says nothing about the shape of returned records or pagination semantics (start_page/max_items) beyond the raw point cost.

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 description coverage is 100%, so all 23 parameters are documented in the schema itself, making 3 the baseline. The description's list of filter dimensions ('price, buy-it-now, condition, region, seller, listing-type, appraisal, shipping filters and sort') roughly maps to the parameter set but adds no syntax or format 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 (Search) and resource (live Yahoo! Auctions Japan listings) and enumerates the filterable dimensions. The word 'live' implicitly distinguishes it from the sibling run_yahoo_auctions_items_closed_search, though no sibling is named 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?

No guidance on when to choose this tool versus the closed-search, product, or category siblings. The only conditional hint is embedded in the schema ('optional when a category is set'), not the description.

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