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

With no annotations provided, the description carries the full burden of behavioral disclosure but fails to address error handling (e.g., domain not found), rate limiting, privacy-protected/REDACTED fields common in modern WHOIS, or the structure of returned data. It only restates the basic operation.

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 description is extremely concise at five words with no redundancy. However, given the lack of annotations and output schema, this brevity leaves significant informational gaps that slightly undermine its structural value despite the efficient phrasing.

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 single-parameter tool with full schema coverage, the description minimally suffices. However, given the absence of an output schema and annotations, it inadequately prepares the agent for common WHOIS complexities such as varying TLD formats, privacy redaction, or connection timeouts.

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% ('Domain to look up'), establishing baseline adequacy. The description adds no additional semantic context about expected formats (e.g., 'example.com' vs 'www.example.com'), validation rules, or constraints beyond what the schema already provides.

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 a clear verb ('Fetch') and specific resource ('WHOIS info'), accurately describing the tool's function. However, it does not explicitly differentiate from sibling network tools like dns_lookup or certificate_info, leaving the agent to infer that WHOIS provides ownership/registrar data rather than DNS resolution.

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?

The description provides no guidance on when to use this tool versus alternatives like dns_lookup, certificate_info, or spf_lookup. Given the overlapping network diagnostic context, explicit guidance on choosing WHOIS for registrar/ownership data versus DNS for resolution would be necessary for a higher score.

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