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

Annotations already declare readOnly, openWorld, non-destructive, and non-idempotent, so the safety profile is covered. The description adds real value beyond them: it enumerates returned fields (availability, registration price, renewal details, registrar link) and warns that missing fields stay unconfirmed and that terms must be verified at the registrar, which explains the non-idempotent hint (prices fluctuate).

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?

Three sentences, front-loaded with the core action and the two input modes, then the return contents, then the caveat. Every sentence carries distinct information with no redundancy.

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 carries the burden of describing returns, and it does so explicitly (availability, prices, renewal, registrar link). It also covers input modes, caveats, and the unconfirmed-field behavior, leaving nothing material for an agent to infer before calling.

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?

Schema description coverage is 100%, and the description's explanation of bare-label vs full-domain input and TLD limiting closely mirrors what the schema already documents. It reinforces rather than extends the parameter docs, so the baseline 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?

The description states a specific verb and resource ('request availability and current quotes for a specific name across supported TLD extensions at once') and explains the two input modes, so the agent knows exactly what the tool does. It does not, however, differentiate itself from the siblings check_availability or find_domains, which an agent might confuse with a multi-TLD availability lookup.

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?

It gives clear usage context: pass a bare label to expand across TLDs, or a full domain to check one, with the tlds parameter as a narrowing option. It stops short of naming alternatives or stating when NOT to use this tool versus check_availability/find_domains.

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