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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the per-match field list (title, brand, model, image, rating), which is useful context, but since an output schema exists this is largely redundant and no scoping or pagination behavior is described.

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?

A single front-loaded sentence with no filler, and the returned-field list is tacked on efficiently. Appropriately sized for a simple search tool.

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 annotations covering read-only/open-world semantics and an output schema covering return shape, the description is adequate for a 2-param search. The remaining gap is entirely on the input side: no parameter semantics at all, which is a real omission given 0% schema coverage.

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?

Both parameters (query, category) have 0% schema description coverage and the description never references them, so the agent gets no signal on query syntax, matching behavior, or how category interacts with query. With low coverage the description should compensate and it does not.

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 ('Costco product search') and even enumerates the returned fields, so the agent knows exactly what it gets back. It does not, however, distinguish itself from siblings like costco_product or costco_categories, which is where a 5 would require sibling routing.

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?

There is no when-to-use guidance and no mention of alternatives such as costco_product (detail lookup) or costco_categories (browsing). The agent must infer from the name alone that this is the entry-point search tool.

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