whois_lookup

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

Description discloses read-only nature, no API key required, rate-limiting, and fallback behavior. Since no annotations exist, description fully bears the burden and does so effectively. No contradictions.

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 concise: two sentences front-loaded with the main action and return fields. Each sentence adds value—purpose, data returned, risk highlights, usage guidance, alternatives, and behavioral notes. 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?

Given a single parameter, no output schema, and no annotations, the description covers purpose, usage, output details, alternatives, and behavioral notes. It is complete for an agent to select and invoke correctly.

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% for the single parameter 'domain'. The description adds critical context: 'A subdomain is normalized to its registrable domain', which is beyond the schema description. This aids correct usage.

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 retrieves domain registration data via RDAP with WHOIS fallback, listing specific data fields (registrar, dates, nameservers, EPP status flags) and risk states. It distinguishes itself from siblings dns_lookup, reverse_dns, and asn_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?

Explicit guidance: use for ownership, lifecycle, and expiry questions. Alternatives are named: dns_lookup for live DNS, reverse_dns/asn_lookup for IP-level ownership. This clarifies when to use this tool versus siblings.

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