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

Annotations already carry readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds genuinely non-redundant context: the exact cost model ('flat 5 points per successful run') and the set of fields returned. It stops short of describing failure behavior for invalid ASINs or missing domains.

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, no filler. The payload and key are front-loaded, and the cost sentence is a single tight clause that earns its place as a decision input.

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 read-only, two-parameter lookup with no output schema, the description compensates well by enumerating returned fields and the cost. What remains thin is the domain default behavior (only in the schema) and there being no mention of failed lookups, which is minor here.

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%: both 'asin' (with an example) and the 19-value 'domain' enum including the amazon.com default are fully documented in the schema. The description adds no syntax, format, or default detail beyond that, 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 and resource ('Get full Amazon product details') and pins the retrieval key ('by ASIN'), plus enumerates the payload fields (title, brand, price, images, rating, features, seller). This separates it from run_amazon_product_search, but it never names or contrasts with run_amazon_product_offers, which also operates per-ASIN.

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-keyed lookup tells an agent to call this when it already has an ASIN, and the 'Flat 5 points per successful run' cost note is a useful routing cue against pricier search alternatives. There is no explicit when-not guidance, no prerequisites, and no named alternative.

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