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

Goes well beyond the annotations: discloses the price ($0.005 USDC on Base), the two-step x402 payment handshake (unpaid call returns MCP PaymentRequired, retry carries PaymentPayload in params._meta['x402/payment']), the legacy _x402_payment fallback, that signing happens in the caller's wallet, and that no match means no charge. It also sets the correct expectation with 'Recommendations, not a safety guarantee.' This is exactly the behavioral disclosure annotations cannot carry.

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 the purpose question and a one-line answer, then pricing/behavioral notes, then a bracketed payment-mechanics block. The bracketed section is dense but cleanly separated, and every sentence carries information. Slightly heavy at the front with the 'ranked by task fit, price and Bazaar-reported repeat buyers' run-on.

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?

An output schema exists so return values need no explanation, yet the description still names what comes back (live price, network, ready-to-call request). Combined with full payment-flow disclosure and the 'no account, no API key' onboarding facts, an agent has everything needed to call this correctly on the first attempt.

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 baseline is 3, but the description adds real meaning on the payment parameter — the two-step flow and where the signed payload goes — which the schema does not explain. It also frames 'task' as the required input and ties 'limit' implicitly to the 'up to 5' return cap.

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 and resource — a live API finder that returns up to 5 x402-paid APIs verified by a fresh unpaid probe with a valid Base USDC 402. The verification and ranking criteria make the operation concrete. It does not, however, distinguish itself from the similarly named sibling 'find_x402_tool' or from 'ontario_task_fit', so an agent cannot route between them from this text alone.

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 opening question 'Which x402 API should my agent call?' implies the discovery use case, and 'Required: task' plus 'No live match, no charge' gives some selection context. But there is no explicit when-not guidance and no mention of the close siblings find_x402_tool, ontario_task_fit, or bazaar_buyer_intent_gap that an agent would need to compare against.

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