Check an x402 endpoint

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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), and the description adds real operational context beyond them: it is free, monitoring refreshes every 30 minutes and includes real test payments, brand-new endpoints may return insufficient_data, and endpoints outside the catalog return monitored: false. These are exactly the edge behaviors an agent needs before trusting a verdict.

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-loads the return contents, then routes to alternatives, then closes with edge cases and a docs link. Six dense sentences, but each carries either routing logic or behavior not present in structured fields; 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?

There is no output schema, so the description's enumeration of return fields (score, grade, verdict vocabulary, uptime, buyer counts) is doing necessary work. Combined with the fresh-endpoint and not-in-catalog edge cases and the API docs pointer, an agent has everything needed to call and interpret this correctly.

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% and the single 'url' parameter is already fully documented in the schema, including the 'exactly as the agent will call it' requirement and an example. The description adds no further parameter meaning, so the 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 and resource ('Get the trust verdict for one x402 endpoint') and enumerates the concrete outputs (score, grade, verdict, uptime, delivery-test status, payout-wallet incidents, buyer count). It explicitly separates itself from check_payment and top_endpoints, so an agent can route without opening any schema.

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 when-to-use ('when you're deciding whether an endpoint is trustworthy at all, before you have a price quote'), an explicit alternative with its trigger condition (check_payment when you already have the 402 quote and are about to pay), and a third route for discovery (top_endpoints). Nothing is left to inference.

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