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

With no annotations, the description carries the full load and does well: it discloses price ($0.02 USDC on base via x402), that no account/API key/invoice is required, the two-call payment handshake, and the provenance of the score (liveness history, on-chain payment evidence, cross-registry corroboration, protocol richness, no self-reported input). It omits failure/refund behavior and idempotency of the paid call.

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?

Four tight sentences, front-loaded with what the tool returns and immediately followed by the pricing/payment mechanics. Little waste; the scoring-input list is dense but informative rather than padded.

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, single-endpoint scoring tool with no annotations and no output schema, the description should ideally characterize the returned score (range, components, confidence). It explains the payment path and methodology but leaves the response shape undefined, which is a real gap when no output schema exists.

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%, so the schema already documents both `id` and `payment`. The description reinforces the meaning of omitting vs supplying `payment`, but adds no syntax or format detail beyond the schema, so 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+resource ('Measured-signal trust score for one endpoint') and implicitly scopes to a single endpoint, which distinguishes it from bulk_score and get_rankings. It stops short of naming a sibling explicitly, so an agent must infer single-vs-bulk routing.

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 concrete invocation guidance for the two-step x402 flow: call without `payment` to get requirements, call again with `payment` to be served. It does not, however, say when to prefer this over sibling tools like bulk_score, get_service_report, or cheapest_that_works.

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