Find paid services

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

Annotations only declare readOnlyHint and openWorldHint; the description adds materially more, including the consent model (limits are the owner's consent, over-limit requests go to the owner for approval), the fact that results are unfiltered listings and not recommendations, and the cost-control instruction to pay only what the task needs. These are behavioral traits an agent could not infer from the annotations.

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 core purpose and return shape in the first sentence, and every subsequent sentence carries operational content. It is on the long side and the payment-confirmation sentence slightly overlaps with what pay_x402 would need to own, but nothing is filler.

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 no output schema, the description compensates by naming the returned fields (url, description, price, how to call it) and the ordering. For a discovery-plus-payment flow across multiple tools, it supplies the full loop: find, pick, pay, answer the owner.

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 already 100%, so the baseline is 3. The description adds genuine query semantics beyond the schema: pass the gist of the request as the query, English works best, and results are ranked best-match-first, plus the max_price_usd scoping constraint restated in prose. It stops short of explaining load-balancing between query and limit, but it is above baseline.

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 ('Search the public x402 catalog... for paid APIs'), names the source (Coinbase's x402 Bazaar), and scopes it to what this wallet can actually pay (USDC on its chain, within max_price_usd). It also lists the return fields and ordering, and the follow-up sibling pay_x402 is named, so it is unmistakable against sibling tools.

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?

Gives an explicit trigger ('use it whenever the owner asks for something you can't answer yourself'), covers phrasing/language variance, and routes the agent onward to pay_x402. It also states a when-not-to-ask-for-confirmation rule tied to wallet limits, which is real operational guidance rather than generic advice.

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