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

Annotations already flag readOnlyHint and openWorldHint, and the description adds real value on top: it discloses the result shape (search link cards plus curated catalogMatches), which URL field to prefer, that searches are English on amazon.com, and that unknown marketplaces fall back to amazon.se rather than erroring. It doesn't mention pagination or rate/remote-call behavior, which keeps it below a 5.

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 core behavior is front-loaded in the first two sentences and the marketplace rules follow in a compact block. The semicolon-chained marketplace sentence is dense but every clause carries actionable information, so little is wasted.

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 an 8-parameter, no-output-schema tool, the definition covers returns and marketplace behavior well but leaves the three enums (climate, tripType, durationBand) unexplained — an agent cannot tell whether they filter results or merely enrich ranking. That gap matters for correct invocation, though the marketplace precision offsets it somewhat.

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?

At 50% schema coverage the description does meaningful work for marketplace and country, spelling out the amazon.com vs amazon.se choice, id aliases like us/se, and the precedence of country then Accept-Language. However, five of the eight parameters — limit, locale, climate, tripType, durationBand — get no explanation of how they affect results, so the coverage gap is only partly compensated.

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 ("Search Amazon for packing items on the user's storefront") and describes the return artifacts (link cards plus curated catalogMatches with /dp links). It does not differentiate itself from the near-mirror sibling suggest_packing_items, so an agent cannot fully disambiguate search vs. suggest from this text alone.

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 context is implied rather than declared: the description explains marketplace selection per user location and says to prefer buyUrl, but never says when to choose this tool over suggest_packing_items, get_catalog, or resolve_product. The closest thing to routing guidance is the marketplace/country fallback chain, which is parameter selection, not tool selection.

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