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

Beyond the readOnlyHint annotation, the description adds meaningful behavioral context: 'Read-only, no authentication required' clarifies access requirements, and 'Every review is tied to a real, verified order line -- only actual buyers can leave one' discloses data provenance and trust guarantees. These are valuable traits not present in the annotations or schema and they do not contradict them.

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 description is composed of three compact sentences, each earning its place: the return payload, the verification/trust characteristic, and the intended use case with auth status. The core purpose is front-loaded, with no redundant or filler wording.

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 one-parameter read-only tool with an existing output schema, this description is complete: it states what is returned, provides trust/verification context, names the decision scenario, and clarifies authentication. There are no missing critical details that would prevent an agent from invoking it correctly.

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?

The single parameter productId is fully covered by the input schema with type, format, pattern, and description 'The product listing's uuid.' Since schema coverage is 100%, the description does not need to add parameter detail, and it does not. Baseline 3 applies when the schema carries the parameter semantics.

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?

The description opens with a specific verb and resource: it returns reviews left for a product by past buyers, and explicitly enumerates the contents (rating, message, date) as well as the aggregate average rating and review count. This clearly distinguishes reviews.list from sibling tools like questions.list or products.search by naming the exact domain object and data being retrieved.

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 description states a clear usage context: 'Useful to judge product/seller quality before advising a buyer on a purchase decision.' This tells the agent when to call the tool, but it does not explicitly contrast it with alternatives or state when not to use it, so it falls short of the explicit exclusion/alternative guidance level.

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