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

Goes well beyond the annotations by disclosing result caps (up to 20), ordering options, the active-only and price-cap semantics, the neutrality guarantee ('our own listings are marked, never boosted'), and the full billing model ($0.002/call, first 25 free, failed calls free). Crucially it explains WHY idempotentHint is false — each call is charged, so repeats are not free — which annotations alone could not convey.

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 purpose and result shape, then usage, example, and cost — a sensible order with no filler. The opening sentence is a long comma-chained clause that is dense to parse, but nearly 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?

Although there is no output schema, the description enumerates the returned fields, the ordering, and the cap, so the agent knows what comes back. Combined with the explicit pricing and the read-only guarantee, nothing material needed to call this correctly 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 coverage is 100%, so the schema already documents all six parameters, and the description mostly echoes them (sort by use or price, price cap, active-only filter, up to 20). It adds no syntax or edge-case detail beyond the schema, and the network filter parameter is only mentioned obliquely as a returned field rather than as a filter. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

Opens with a specific verb and resource: 'Find pay-per-call x402 APIs for a task across the whole Coinbase Bazaar', and enumerates the returned fields (name, URL, method, price, networks, payers, calls, last paid). This is far more specific than any sibling utility tool in the list, so an agent can distinguish it immediately.

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?

Explicit trigger is given: 'Use when an agent needs a paid tool it does not have yet', plus a concrete query example (q=email verification). It lacks any when-not-to-use or exclusion guidance, but no sibling tool overlaps in function, so the absence costs little.

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