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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context on top: it is free, reflects monitoring on a 30-minute cadence plus real test payments, fresh endpoints can return 'insufficient_data', and out-of-catalog endpoints return monitored: false rather than an error. These are behavioral traits an agent cannot infer from annotations or schema.

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 return payload, then routing guidance, then operational caveats. Despite being several sentences, each one carries distinct decision-relevant information with no restatement of the name or schema.

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 further explanation; the description nonetheless defines the verdict enum values (proceed, caution, avoid, free, insufficient_data), which is exactly the interpretive context a caller needs. Edge cases for unknown and brand-new endpoints are both covered.

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 fully documented in the schema (full URL including path, as the agent will call it), so the description correctly does not re-explain it. The description adds no format or normalization detail beyond the schema, 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. It is immediately distinguishable from check_payment, top_endpoints, and get_full_report 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 explicit routing: use this when judging trustworthiness before a price quote exists; use check_payment when you already hold the 402 quote (amount and payTo) and are about to pay; use top_endpoints to discover rather than check a known endpoint. The when/when-not conditions and the alternatives are all named.

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