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

No annotations are provided, so the description bears the full burden. It usefully discloses the returned data set and the zero-cost trait, and the operation is implicitly read-only, but it says nothing about failure modes (unsupported TLDs, missing WHOIS records) or whether the query is live.

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?

A single front-loaded sentence that opens with the cost badge and then enumerates the exact data retrieved. No filler; every clause earns its place.

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, the description compensates well by listing the return fields (age, creation, expiration, registrar, nameservers). It is nearly complete for a simple one-parameter read lookup, falling short only on error/degradation behavior.

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?

There is a single parameter with 100% schema description coverage, so the baseline is 3. 'For any domain' adds only mild reassurance about input generality beyond the schema's own example.

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?

States a specific verb (looks up) and resource (WHOIS registration details, domain age, creation date, expiration, registrar, nameservers). The scope is unambiguous, though it never explicitly distinguishes itself from siblings like check_dns_and_headers or check_web_hosting.

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 only usage signal is the 'FREE:' prefix, which tells the agent there is no cost concern. There is no statement of when to choose this over the sibling DNS/hosting/noindex tools, and no prerequisites or exclusions.

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