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

With no annotations, the description carries the full burden. It reveals the data source (who.is) and the narrow existence-check scope, but it does not disclose behavior for invalid domains, query formats, rate limits, or response shape beyond what the output schema may cover.

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 short and the key qualifier ('existence') is present, but it opens with 'WHOIS Check:', which redundantly repeats the tool name and title. It is compact rather than genuinely information-dense.

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?

For a tool with one undocumented parameter, no annotations, no required fields, and a large family of WHOIS-related siblings, the description is too minimal. An agent cannot confidently determine what to pass for q or when to prefer this tool over whois/whoisserver.

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 0%, so the description must compensate. It implies the query 'q' is a domain name, but never explicitly states that q takes a domain, the expected format, or the meaning of an empty default value. This is thin for an agent trying to construct a correct call.

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?

States a specific verb ('check'), resource ('Domain WHOIS record existence'), and source ('via who.is'). This distinguishes it somewhat from full-record siblings like whois and whoisserver, though 'check' is generic and the exact result is not described.

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?

No guidance on when to use this tool versus the many related siblings (whois, whoisserver, rdap_domain, ipwhois). The phrase 'existence via who.is' hints at a lightweight existence check, but no explicit when-to-use or alternative routing is provided.

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