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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and open-web profile is covered. The description usefully discloses the two return shapes (PA-API products or search deep-link cards) and the odd operator note about omitting `?tag=` until real Associates IDs exist, but it says nothing about rate limits, pagination, or empty-result behavior for an open-world Amazon search.

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?

Three tight sentences with the resource and scope front-loaded, and the required-input constraint placed before the alias note. The parenthetical about `?tag=` is dense but earns its place as an implementation caveat; only minor wasted phrasing.

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 9-parameter, no-output-schema tool the description does compensate where it matters most: it says what comes back (products vs. deep-link cards) and confirms required inputs. The remaining gap is filter semantics for the optional facet parameters, which an agent would need in order to call it precisely.

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 78%, so the schema carries most parameter meaning and the baseline of 3 applies. The description only reinforces marketplace and locale as required, and adds nothing about `stage`, `species`, `sizeBand`, `budgetBand`, or `kitCategory`, including whether those filters are strict or just ranking hints.

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 (search) plus the resource (pet welcome-kit / first-30-days supplies) and the scope (a specific Amazon marketplace). It also names the alias `search_kits`, which helps the agent match a sibling-looking name, but it never explicitly contrasts with `resolve_product`, which is the nearest ambiguous sibling.

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 prerequisite ('Requires marketplace + locale') is stated, which is real guidance. However, nothing tells the agent when to pick this over `resolve_product` (keyword search vs. known product id) or when a deep-link card is preferable to PA-API products.

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