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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description still adds substantive behavior: the reliability threshold (≥30 paid calls, zero failures) and result ordering (most-called first). It stops short of describing the seller record fields or result-set size handling.

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 sentence with no filler, front-loaded with the usage trigger and followed by the return criteria. Every clause carries information an agent needs.

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 safety, schema covering both params, and no output schema, the description supplies the necessary return semantics (reliability definition and ordering). It lacks detail on what a seller record contains, a minor gap given the tool is a discovery/list operation.

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% with only two optional params, and the schema documents both limit and category including the enum values. The description repeats the category options and adds that the filter is optional, but contributes no format or semantics beyond the schema, so baseline 3 applies.

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 (List) and resource (reliable x402 sellers) and operationalizes 'reliable' with concrete criteria: zero failures across at least 30 paid calls. The scope and ordering (most-called first) let an agent distinguish this from check_x402_seller, which evaluates a single seller.

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?

Opens with an explicit trigger: 'Call this when choosing among sellers for a task, or when the user asks for a safe or reliable API.' Clear context for use, though it does not name sibling alternatives or state when not to use it.

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