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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the description's job is to add beyond that. It usefully discloses that prices are checked live, localized to the shopper's country/currency, and drawn from a named set of retailers. However 'checked live' from external marketplaces sits in tension with openWorldHint=false, and no rate-limit, caching, or fallback behavior is described.

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, but the first two restate the title ('Cheapest Price. Lowest current price for a product, with compare links') and the third opens by repeating 'The lowest current price for a product' a third time. The genuinely new information (source retailers, live check, geo/currency localization) only appears after that redundancy.

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 carries the burden of describing returns and does so adequately: prices in the shopper's currency plus comparison links to Amazon and local shops. It is reasonably complete for a single-purpose lookup, missing only guidance on failure/empty-result behavior.

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 q, used, and country are already fully documented and the baseline is 3. The description reinforces that results are localized to the shopper's country and currency and that eBay can include used items, but adds no syntax or format detail the schema lacks.

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 (lowest current price for a product) and names the concrete sources (eBay, Best Buy in the US, Amazon, local shops) plus compare links. This clearly separates it from same-domain siblings like medbillcheck_check_price (medical) and pricedropback_check_price_drop_claim (promo claims).

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 (query a product to get the cheapest live retail price) but the description never states when to use this versus a sibling, nor any exclusions or prerequisites. No alternative tool is named for a near-miss query.

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