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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds one genuinely useful behavioral fact, the '10 credits' cost, but says nothing about auth requirements, failure modes for invalid ASINs, or response latency for a scraping tool.

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 sentence plus a cost clause; the resource and the ASIN key are front-loaded and nothing is padded. Every clause earns its place.

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?

There is no output schema, and the description compensates well by enumerating the fields an agent can expect. For a single-parameter read tool with annotations covering safety, the remaining gaps (ASIN format, error handling) are minor.

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 0% and the single parameter is undescribed in the schema, so the description must carry the load. 'By ASIN' clarifies what the lone parameter is, but the ASIN format (length/charset expectations) and validation behavior are left unstated.

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?

The description names a concrete resource ('Amazon product page') and scope ('by ASIN'), then enumerates the returned data (price, rating, availability, bullet points, specifications, photos, variations). That enumeration implicitly separates it from the plural/list and search siblings. It stops short of naming a sibling or stating an explicit action verb, so not a 5.

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 only implied: the ASIN-scoped phrasing signals a single-product lookup. There is no when-to-use vs. when-not guidance and no mention of amazonProducts, amazonSearch, or amazonRankings, leaving the agent to infer the boundary between this tool and its very similarly named siblings.

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