domain_check

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

No annotations exist, so the description carries the full behavioral burden. It usefully discloses the paid x402 model at $0.002 per call and that every signal is returned with its source, which is real added context. However it does not state that the operation is purely read-only, nor anything about latency, caching, or failure behavior.

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?

Two compact sentences plus a price line, with the core question front-loaded and the signal list immediately following. Every clause carries information; nothing is 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?

With no output schema and no annotations, the description partially compensates by enumerating the returned signals and stating each comes with its source, and it flags the payment requirement. It is close to complete for a paid read-only lookup, with only the safety profile and latency left unstated.

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 'domain' (domain or full URL) and 'payment' (signed x402 payload). The description adds no format or syntax detail beyond implying links/URLs are acceptable, so baseline 3 is appropriate.

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 opens with a specific question ('Is this link safe?') and then enumerates exactly what it inspects: domain age/registrar via RDAP, DNS, TLS certificate, and brand lookalikes. That is a concrete verb+resource combination an agent can distinguish from neighbors like email_check or threat_intel, though it never explicitly names a sibling to contrast against.

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?

Usage is implied by the framing question: call this when you have a domain or URL and want a safety verdict. There is no explicit when-not guidance, no statement of alternatives, and no note about when another sibling (e.g. email_verify, impostor_check) would be the better choice.

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