WHOIS Lookup

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

With no annotations provided, the description carries full burden. It discloses key behavioral traits: it's a read operation that returns registration data, notes that ownership info may be redacted, and implies it queries external WHOIS databases. However, it doesn't mention rate limits, authentication needs, error conditions, or response format details.

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 efficiently structured in two sentences: the first states the core functionality with specific data fields, the second provides usage contexts. Every phrase adds value with zero redundant information, making it easy to parse and understand quickly.

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 single-parameter read tool with no output schema, the description provides good context: it explains what data is returned, when to use it, and limitations (redacted ownership). It could be more complete by mentioning response format or error handling, but covers the essential aspects well given the tool's simplicity.

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% with a single well-documented parameter, so the baseline is 3. The description doesn't add parameter-specific information beyond what the schema provides (domain name format, constraints), but it does reinforce the tool's domain-focused purpose.

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's purpose with specific verbs ('Get WHOIS registration info') and resources ('domain'), listing exact data fields returned (registrar, dates, name servers, ownership, DNSSEC status). It distinguishes from siblings like dns_lookup by focusing on registration metadata rather than DNS resolution.

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 clear context for when to use this tool ('domain research, expiry monitoring, detecting recently registered domains'), including specific use cases like phishing detection. However, it doesn't explicitly state when NOT to use it or name alternatives among siblings (e.g., when to use dns_lookup instead).

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