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

The readOnlyHint annotation already establishes this as a safe read, so the description is not carrying the safety burden. It does add useful scope by naming the returned record fields, but it says nothing about lookup failures, redacted registries, or rate limits, which are common WHOIS behaviors.

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?

One dense sentence with the resource front-loaded and no filler; every listed field earns its place given there is no output schema. The fragmentary phrasing is terse rather than wasteful.

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, annotation-covered tool with no output schema, enumerating the returned fields is exactly the missing piece an agent needs. The only gap is that it does not note failure modes or how it differs from get_domain_age.

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 ('Domain, e.g. example.com'), so the schema fully documents it. The description adds no format or normalization detail beyond the schema, making the baseline 3 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?

States a specific verb and resource (WHOIS lookup for a domain) and enumerates the fields returned, which lets an agent distinguish it from a bare domain-age check. It does not explicitly contrast itself with the overlapping sibling get_domain_age, so it falls short of the top tier.

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 when-to-use guidance, no prerequisites, and no mention of alternatives such as get_domain_age, which returns a subset of this data. The agent must infer from the field list alone that this is the broader lookup.

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