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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds the important interpretation that null means the marketplace does not report that signal, which helps the agent avoid misreading missing data as a problem.

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 sentences deliver the core purpose, the null semantics, and a cross-reference to a sibling tool with no filler. Everything 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?

Annotations cover safety and idempotency, an output schema exists, parameters are fully documented, and the description provides the one interpretive detail an agent needs: what null means. Nothing essential is missing.

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 description coverage is 100%, so parameters are already fully documented in the schema. The description does not add much beyond indicating the seller context; per the rubric, baseline 3 is appropriate when the schema carries the parameter-semantics load.

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?

Description opens with a specific verb-resource pair ('Look up a seller's trust signals') and enumerates concrete signal types. It also names list_seller_listings as the sibling for current offerings, which distinguishes this tool from a nearby alternative.

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 implies the tool is for trust/verification data rather than active listings, and explicitly points to list_seller_listings when the agent needs current offers. It provides a clear context signal, though it does not spell out exhaustive when-not-to-use conditions.

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