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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral detail beyond them: partial-failure semantics ('a product that can't be checked carries an error and message instead'), output ordering ('in input order'), and the output contract ('signals only, never a buy or avoid verdict'). It does not mention auth or rate limits, but for a read-only tool that is a minor gap.

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?

Front-loaded with the triggering scenario before the mechanics, and the return contract and exclusions follow in a logical order. It is a dense single paragraph with a few near-redundant clauses (e.g. restating the field list already in the schema), so not quite a 5.

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 batch read-only tool with an output schema present, the description covers everything an agent needs: trigger, batch size, input expectations, output ordering, partial-failure behavior, and scope exclusions. Return-value shape is correctly left to the output schema.

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 100%, so the baseline is 3, but the description adds framing the schema does not: the fields should be 'what you already read from its listing' (i.e. do not fetch anything new), the 20-item cap, and that the caller-supplied id is 'to match results'. That is useful guidance layered on top of the per-field descriptions.

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 (check multiple product listings for trust signals) and explicitly distinguishes itself from the singular sibling: it returns 'the same findings as check_product for each' product. An agent can tell immediately this is the batch counterpart to check_product.

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?

Gives an explicit trigger ('when the user is comparing several product listings, such as search results or the same item at different stores') and explicit exclusions ('Not for banking, health, government or email pages'). The batch-vs-single routing versus check_product is also stated.

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