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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description's addition of the two modes and the WhoisXML source adds useful behavioral context. No contradictions found.

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 sentence that is front-loaded with the core purpose and includes key differentiators. No filler or 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?

Given the tool's simplicity (2 parameters, robust annotations, and an output schema), the description sufficiently covers all aspects. It explains the two modes and the data source, leaving no gaps in understanding.

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 coverage is 100% with descriptions for both parameters. The description adds value by explaining the trade-off between DNS_ONLY and DNS_AND_WHOIS, and provides example domain formats, going beyond the schema's enumerations.

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 the tool checks domain availability with two modes (fast DNS or thorough DNS+WHOIS). It distinguishes itself from siblings like whois.domain.lookup which provide full WHOIS data, by focusing specifically on availability for registration.

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?

The description provides guidance on when to use each mode: DNS_ONLY for speed, DNS_AND_WHOIS for accuracy. It does not explicitly state when not to use the tool or mention alternatives, but the mode descriptions give clear context for usage decisions.

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