Pre-flight check

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

Beyond the readOnly/idempotent/openWorld annotations, it discloses the commercial barrier (Pro key or x402 at $0.01 per call), that the server will not pay on the caller's behalf, and that a keyless call degrades into an explanation of what is required rather than a result. It also reassures that the URL argument triggers no fetch of the target host.

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 fact inventory is front-loaded and every listed item maps to an actual output field, with payment terms placed last where they belong. The opening sentence is long and list-heavy, but no clause 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?

With no output schema present, the description carries the return-value burden and mostly discharges it by enumerating the facts returned, and it covers auth/payment and the keyless fallback. It does not say how multiple matching listings are shaped or paginated, which is a modest residual gap for a four-parameter, nested-object tool.

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 coverage is 100%, so the baseline would be 3, but the description adds a real constraint not encoded in the schema: 'Give exactly one of agent, wallet or url' — the schema declares no properties as required and has no oneOf/anyOf, so this XOR rule is unique value. The chain/agent exclusion is repeated from the schema rather than added.

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 returned — first-seen date, recorded ownership changes, revoked-rating share, wallet-registered listing count, evidence level — so the vague name 'check' is fully disambiguated. It never names a sibling (search_agents, get_agent, get_agent_history), so the agent must infer that this is the trust/forensics read rather than a profile lookup.

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?

'Dated facts to read before you pay or rely on an agent, a wallet or an endpoint' gives a clear situational trigger, and 'Facts only: there is no score and no verdict' pre-empts the wrong expectation. It stops short of routing language against the sibling tools, so the agent gets context but no explicit alternative selection rule.

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