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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds genuinely useful non-annotation context: '1 point per returned record,' disclosing the credit cost of a call, plus the fact that results carry realized sold prices.

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 sentences, front-loaded with the primary purpose and scoping, with the cost note compactly appended. The filter enumeration slightly overlaps the schema but stays brief and readable.

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 14-parameter search tool with no output schema, the description conveys the domain (Japanese closed auctions), what the results mean (realized sold prices), and the call cost. It omits mention of pagination (start_page/max_items) and page-size behavior, which would help for a paginated result set, keeping it short of a 5.

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 every one of the 14 parameters is already documented in the schema, including enums and defaults. The description's listing of filter categories (sold-price, condition, region, seller-type, sort) adds no formatting or semantics beyond what the schema provides, so baseline 3 applies.

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: search COMPLETED Yahoo! Auctions Japan listings by keyword and see actual sold prices. The 'completed/closed' scope implicitly distinguishes it from the active-listing sibling run_yahoo_auctions_items_search, but it never names that sibling to make the contrast explicit.

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?

Usage is implied by the 'completed auctions... price each item actually sold for' framing, which signals this is for historical sold-price lookups rather than active listings. There is no explicit when-to-use/when-not statement or named alternative, so the routing is left to inference.

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