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

With no annotations, the description carries the full burden: it usefully discloses that registrant info may be redacted ('if public'), which is real behavioral context. However, it says nothing about rate limits, upstream WHOIS server variability, failure behavior for unregistered domains, or latency — gaps an agent should know before calling.

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 short sentences, front-loaded with the action and followed by the return payload; nothing is padded. Slightly more useful structure (e.g., a note on input format) could have earned the last point without bloating it.

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 read-only lookup with no output schema, the description covers what it does, what inputs it accepts, and what fields come back, including the redaction caveat. An agent has enough to call it correctly without further context.

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?

The single 'query' parameter is fully documented in the schema ('Domain name or IP address to look up'), so the schema does the work. The description repeats the same accepted input types without adding format detail (e.g., no scheme, no port, bare domain only), which is the baseline case for 100% coverage.

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 names a specific verb and resource ('Query WHOIS registration info') and enumerates the returned fields, making the tool's function unambiguous. It falls short of 5 because it never distinguishes itself from the closely named sibling lookup_ip, which also accepts IP addresses — an agent must infer the difference.

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 only implied by 'for a domain name or IP address'; the description does not state when to prefer this over lookup_ip or resolve_dns for the same input. No exclusions, prerequisites, or error cases (e.g., unregistered domains, private registrations) are mentioned.

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