Domain WHOIS

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

No annotations are provided, so the description carries the full burden. It discloses the kind of data returned but does not mention potential limitations such as privacy redaction (e.g., GDPR), rate limits, or behavior for invalid/nonexistent domains. The description is accurate but not rich in behavioral detail.

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 sentences: the first explains what the tool does and the data it returns, the second gives a concrete use case. No redundant information or fluff, well front-loaded.

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 simple one-parameter lookup with no output schema, the description covers the purpose, the kind of data returned, and a practical use case. Minor gaps such as error handling or data availability caveats are not covered, but the tool's simplicity means this is mostly complete.

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% for the single 'domain' parameter, which already has a clear description with an example. The tool description adds no additional parameter semantics beyond what the schema provides, 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 uses specific verb 'Fetch' and resource 'WHOIS registration data for a domain', listing expected data fields (creation/expiry dates, registrar, nameservers, registrant). This clearly differentiates the tool from IP-focused siblings like ip_geolocation and proxy_check.

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?

It provides an explicit use case: 'Use this to judge how old or trustworthy a domain is, e.g. when vetting a sender or website.' However, it does not explicitly mention alternative tools or situations where this tool should not be used.

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