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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds useful context beyond that: it pins the marketplace to amazon.com and specifies the content types returned (pricing, availability, inline review samples, descriptive content), which is meaningful behavioral scope for a detail lookup.

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?

The opening sentence is well front-loaded and earns its place. However, the 'currency: ... Default USD. Allowed values: USD.' and 'language: ...' lines duplicate the schema descriptions verbatim, adding bulk without new information.

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?

An output schema exists, so return values need not be detailed, and annotations cover the safety profile; the description still adds the domain scope and content summary. For a single-ASIN lookup with full schema coverage this is nearly complete, though it omits edge-case behavior (e.g., invalid or unavailable ASIN).

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 the schema already documents all three parameters. The description's currency/language lines simply restate the defaults and allowed values verbatim rather than adding syntax, format, or usage nuance, so the baseline of 3 is appropriate.

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 ('Returns normalized product details for an Amazon ASIN') and enumerates the content returned (pricing, availability, overview, review samples, descriptive content). It also scopes the marketplace to amazon.com and names amazon_search as the sibling for discovery, so an agent can distinguish it without opening the 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?

Explicitly routes search intent to amazon_search ('Use amazon_search to search Amazon products'), which clarifies when not to use this tool. It implies the ASIN is the lookup key but does not state prerequisites such as needing a valid 10-char ASIN or a prior search step, so it falls short of full when/when-not guidance.

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