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

Annotations already declare read-only, idempotent, open-world behavior, so the description does not need to repeat that. It adds meaningful context: data comes from RDAP or WHOIS, results are cached for up to an hour, owner disclosure varies by registry, and TLD-specific field semantics are explained.

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 front-loaded with the core purpose and contains no filler. It is dense and parenthetical-heavy, making it slightly harder to scan, but every clause carries useful information.

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 does a good job explaining the returned fields, data source, caching, and privacy caveats. It could mention error or not-found behavior, but it is otherwise complete for a simple read-only lookup.

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 domain parameter is fully documented in the schema, so the baseline is 3. The description adds TLD-specific interpretation of returned fields but does not add input-format or validation guidance beyond the schema.

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 clearly states that this returns a registry record for a single domain and enumerates the main fields. It is distinguishable from broad search tools, but it does not explicitly differentiate itself from sibling tools like check_domain or check_domains.

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 explicit guidance on when to use this tool instead of check_domain, check_domains, or other siblings. Usage is only implied by the phrase 'registry record about one domain' and the listed fields.

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