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

Annotations already declare idempotency and non-destructiveness, and the description goes well beyond them: it discloses that this is a paid call ($222.00 USDC on Base/Arbitrum One), the required x402 v2 PAYMENT-SIGNATURE header, the POST-to-paid_url invocation pattern, and a docs link. The one gap is that it does not say the paid action is charged even on a check failure or what happens on payment rejection.

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 value proposition and kept to a few dense sentences with zero filler. The fragment 'One check: the tool alone.' is cryptic and the 'document_hash optional' clause duplicates the non-required schema status, costing a little clarity.

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?

For a paid multi-check aggregate with an output schema, the description covers cost, payment protocol, auth header, idempotency, and the receipt artifact. Missing only the semantics of the 'trust verdict' field and error/refund behavior, which an agent paying per call would want.

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%, including detailed idempotency-key semantics and the SHA256 pattern, so the schema carries the parameter burden. The description adds almost nothing beyond restating that document_hash is optional and implying the doc timestamp depends on it.

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 enumerates exactly what is bundled (liveness, content, TLS fingerprint, trust verdict, document timestamp) and the result form (one signed receipt), which is more specific than a vague 'run checks'. However it never names the sibling single-check tools (trust_report, trust_preflight, check_url_custom) it is an aggregate of, so differentiation is only implied by 'One check: the tool 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?

'One check: the tool alone' implies that single-purpose checks belong to other tools, but no sibling is named and no explicit when-not condition is given. The payment prerequisites (x402 v2, PAYMENT-SIGNATURE header, price) are clear but they are invocation mechanics, not selection guidance.

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