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

The annotations already provide readOnlyHint=true and openWorldHint=true, and the description adds that the tool produces a ranking and is not purchase advice. That is helpful but does not go deeper into what the marketplace-evidence score means, what the returned ranking contains, or any caveats about ranking quality.

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?

Two short sentences with no filler. The primary behavior is front-loaded, and the 'not purchase advice' sentence is a concise and relevant clarification that earns its place.

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?

The description is adequate for a simple read-only comparison tool, but since there is no output schema, it should say more about the expected result shape and interpretation of the evidence score. The ranking behavior is mentioned, but a calling agent is left guessing about formatting and scoring details.

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 description only gestures at 'retailer listings' and the 2–20 range, with no direct explanation that each entry needs a retailer choice and a product_id, even though those are meaningful for correcting invocation. The schema's nested properties are helpful, but with schema description coverage reported at 0%, the description should compensate more than it does.

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 states a specific action ('Compare'), a bounded resource ('2–20 retailer listings'), and the distinguishing outcome ('rank them by marketplace-evidence score'). This makes it clear this is a multi-listing comparison rather than single-item trust checking, so it is easily separated from the sibling check_product_trust.

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 intended use is implied: use it when comparing several retailer listings and ranking them by evidence score. The 'not purchase advice' disclaimer is a useful exclusion, but the description never names when to prefer check_product_trust or gives explicit when-not guidance beyond the disclaimer.

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