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 that this is a read-only network lookup via RDAP and indicates the kind of response fields expected, but it does not mention output format, failure behavior, or whether input is required despite both parameters being optional.

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 a single front-loaded sentence with no filler. It packs the action, protocol, and expected result fields into a compact format that is easy to scan.

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 simple read-only lookup, the description is mostly adequate, but because there is no output schema it only partially explains what is returned. It also leaves ambiguity around the two optional parameters and how to choose between them.

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%, so the schema already documents both parameters. The description adds context that this is a WHOIS lookup, but it does not clarify the distinction between 'host' and 'domain' or explain which parameter should be supplied in which scenario.

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 a specific action ('WHOIS domain registration lookup') and resource ('domain'), and names concrete data fields (registrar, dates, nameservers). It is unambiguous, though it does not explicitly differentiate itself from sibling tools like registrar-lookup or domain-age.

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 is given on when to use this tool versus alternatives such as registrar-lookup, domain-expiry, or ns-lookup. The description implies it is for WHOIS/RDAP data but provides no exclusions, prerequisites, or selection criteria.

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