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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavioral context beyond annotations: result count per page (~16), full return field list, and a billing rate ($0.005/request). Missing pagination cap (though schema shows page max 20) and rate-limit info.

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?

Four tight sentences, front-loaded with the core purpose, then output fields, then filters, then the routing hint and pricing. Every sentence carries information; no filler.

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-param search tool with no output schema but full schema coverage, the description covers purpose, filter categories, return fields, pagination size, sibling routing, and cost. An agent has everything needed to select and invoke correctly.

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% and the schema itself documents defaults, enums, units, and formats. The description summarizes which filters exist (category, price, condition, brand, seller, Prime, deals, 4+ stars) and reinforces the currency context ('in the marketplace currency'), adding light value over the schema. Baseline 3 is appropriate but the enumerative filter summary plus currency framing push it slightly higher.

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 (Amazon products), names the input modes (keyword or ASIN), scope (24 marketplaces), and explicitly distinguishes from the sibling amazon_product_details. An agent can immediately tell this apart from amazon_best_sellers and amazon_product_details.

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?

Names the alternative for single-product lookups ('Use amazon_product_details for one product'), giving clear routing context. However, it does not position against other Amazon siblings like amazon_best_sellers or amazon_seller_products, so routing among the full Amazon family is incomplete.

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