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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds genuinely new context the annotations cannot: per-request billing ($0.005) and an enumeration of returned fields (pricing, buy box/seller_id, availability, reviews). It doesn't mention rate limits or failure modes, but the cost disclosure is the key non-structural trait.

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?

Front-loaded with the verb+key input, followed by a dense return-value enumeration, then the billing note. Every clause earns its place, though the return list is long enough to read as a run-on rather than sharply prioritized.

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 must convey return shape, and it does so thoroughly (pricing, buy box with seller_id, availability, condition, media, specs, ratings, reviews). Combined with billing and input provenance, an agent has everything needed to invoke and interpret the call.

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% with only 2 params, so the baseline is 3. The description adds value by tying ASIN to its origin (search_amazon_products), which the schema does not explain, clarifying the expected input provenance beyond the raw format example.

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 ('Get') and resource ('Amazon product by ASIN') and immediately distinguishes itself from the sibling search_amazon_products by naming it as the ASIN source. An agent can tell this is a details-lookup, not a discovery tool, without opening either schema.

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?

The parenthetical '(from search_amazon_products)' gives clear context that this tool follows a search step, which is useful routing guidance. It stops short of stating when not to use it or what to do if the ASIN is unknown/expired, so no explicit exclusions.

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