x402 trust score for an endpoint (paid)

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

No annotations are provided, so the description fully carries the transparency burden. It discloses live-probing for uncataloged endpoints, the low-confidence first-contact flag, the latency measurement from a single EU vantage point, the meaning of 'unverified' (unknown, not bad), and the expectation that payTo/price may vary for templated endpoints. It also warns that provider-advertised claims are unverified.

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?

The description is a single dense paragraph with no visual structure, making it harder to scan. Every sentence does convey distinct information, but the lack of bullets, sections, or numbering hurts readability. It is comprehensive but not concise; the sheer length may overload an agent trying to quickly extract key usage rules. It earns a 3 as a minimum viable score for structure.

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 must explain return values, and it does so thoroughly: it lists the score, grade, verdict, price, scoreRange, flagsDetailed, component breakdown, provider claims, and 30-day stats. It covers edge cases (parameterize, unverified, not-payable) and caveats (latency, payTo variation), making the tool's behavior and outputs fully understandable for an agent.

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?

Although the schema already describes `resource` as a full x402 resource URL, the description adds substantial nuance: it gives an example, explains how uncataloged endpoints are probed, and details how template placeholders like {slug} or :slug are treated with a 'parameterize' verdict. This goes well beyond the schema's simple description and helps the agent understand both the format and behavioral expectations for the input.

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?

The description clearly states it computes a trust score for a SPECIFIC x402 endpoint, with a verdict, price, and structured flags. It explicitly contrasts with broader tools by emphasizing specificity ('SPECIFIC x402 endpoint') and saying 'One call answers WHETHER and at WHAT PRICE to use an endpoint', which differentiates it from siblings like x402_ecosystem_stats or x402_trust_bulk.

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?

It gives explicit when-to-use guidance: 'Call this BEFORE paying an unknown x402 endpoint to avoid dead, fraudulent, or recently-hijacked services.' It also provides decision rules for each verdict (parameterize, unverified, not-payable), telling the agent what actions to take or not take for each case, and notes when auto-pay occurs vs. returning a quote.

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