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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety and external-dependency behavior are covered. The description adds the shape of the result, but says nothing about registry rate limits, thin-registry/partial results, or failures for unregistered domains, which matter for an open-world 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?

A single front-loaded sentence identifying purpose and payload with no filler. Every clause earns its place by naming a returned field.

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 usefully enumerates the returned fields, which is the main completeness burden here. It falls short only on edge-case behavior (unregistered domains, rate limiting) that an agent calling an open-world WHOIS service would benefit from knowing.

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 required parameter with 100% schema description coverage, so the schema already carries the meaning. The description adds nothing about domain syntax or whether IDNs/subdomains are accepted, so the baseline of 3 applies.

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?

Names a specific resource (domain) and enumerates exactly what the summary contains: registrar, created/updated/expires dates, nameservers, DNSSEC, status flags. It does not, however, contrast itself with siblings such as get_domain_age, which covers an overlapping concern.

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 statement of when to use this versus alternatives, no prerequisites, and no exclusions. An agent can infer it is a per-domain lookup from the name, but nothing routes it away from get_domain_age or check_spoofability.

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