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

With no annotations provided, the description carries the full burden. It discloses the WHOIS-based method, the scope (popular TLDs, typo-squat variants), and the 40-variant cap to manage latency. This is transparent about what the tool does and its limitations, though it doesn't mention any potential side effects or that it is read-only (which is implied).

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 two sentences, front-loaded with the primary purpose, and includes the cap and TLD list efficiently. There is no fluff; every clause adds useful information without 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?

The tool has no output schema, so the description must cover the main functional aspects. It explains what is checked, the variants, the TLDs, and the latency cap. It does not describe the return format, but for a tool of this type, the description is sufficiently complete for an agent to invoke it correctly without ambiguity.

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% (both parameters documented). The description adds value by clarifying the checkSquats behavior with concrete examples (adjacent-key substitution, etc.) and the list of TLDs, which enriches understanding of what the tool will scan. This exceeds the baseline and helps the agent set parameters correctly.

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 ('Check whether') and resource ('a domain is registered') plus an additional action ('scan common typo-squat variants'). It lists the specific TLDs and variant types, making it clearly distinct from sibling tools like domain_health_check or domain_report, which focus on other aspects.

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 gives clear usage context: 'for brand-protection or domain-flipping research'. It also discloses the WHOIS-based nature and the 40-variant cap, which helps an agent decide if this tool fits the task. However, it does not explicitly name alternatives or state when to prefer another tool, though the context is sufficient for typical selection.

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