Domain whois (RDAP)

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

Annotations already cover the read-only, idempotent, open-world safety profile, and the description adds non-annotated traits: a 6-hour cache and the 'error' field returned for ccTLDs without public RDAP. It stops short of describing rate limits or whether results can be stale within the cache window.

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?

Front-loads the resource and returned fields, then usage, then the caveat and caching note. Every sentence earns its place with no padding.

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?

There is no output schema, so the description compensates by enumerating the returned fields and explaining the error shape for unsupported ccTLDs. For a single-parameter lookup tool, an agent has everything needed to call it and interpret results.

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% and the single parameter is already documented including the 'full URL works too' nuance, so the schema carries the load. The description adds nothing further about the domain argument, making the baseline 3 appropriate.

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/resource (registration info for a domain via RDAP) and enumerates the exact fields returned (registrar, dates, nameservers, status codes, abuse contact). It also explicitly distinguishes itself from ip_whois and asn_lookup, the sibling tools an agent might otherwise confuse it with.

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?

Gives both a positive trigger ('Use for who registered a domain and when it expires') and an explicit routing rule for the alternative ('For who hosts it, run ip_whois or asn_lookup on its IPs'). It even covers the failure case for ccTLDs like .ro and .de, so the agent knows what an error result means.

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