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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds useful behavioral context by specifying the exact response fields and the computed 'age in years', which is valuable because no output schema exists. It does not detail failure modes such as unknown domains, but this is a minor gap for a simple read-only lookup.

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 a single sentence that delivers the key semantic content upfront: it is public WHOIS data, followed by the returned fields. There is no wasted wording or irrelevant detail.

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 one-parameter read-only tool with complete annotations and an in-description output field list, the description is largely complete. The only notable omission is guidance on when to prefer a sibling DNS/WHOIS tool, but that is a routing concern rather than a calling-context gap.

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 parameter 'domain' is fully described in the schema with an example, so schema coverage is 100%. The description mentions WHOIS data but does not add any extra meaning beyond the schema, so the baseline score of 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 states a clear resource ('Public WHOIS profile') and enumerates the data returned: registrar, creation date, expiration, name servers, and age in years. It is easy to understand what the tool does, though it lacks an explicit verb and does not differentiate itself from dns_profile or dns_lookup among the siblings.

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?

There is no guidance about when to use this tool instead of siblings such as dns_profile, dns_history, or dns_lookup. An agent must infer the intended use from the name and description, with no exclusions or explicit conditions.

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