whois

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

With no annotations, the description takes on the full burden. It discloses the underlying protocol (RDAP) and the type of data returned, which provides useful behavioral context beyond the tool name. It doesn't mention rate limits or error handling, but for a read-only lookup these are not critical omissions.

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 sentence of about 12 words, front-loaded with the action and object. Every word adds value, with no repetition or filler.

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?

The tool is simple (one required parameter) and has an output schema, so return value details are covered. The description fully explains the tool's purpose and method. Minor gaps like TLD support or error cases are acceptable given the output schema and 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?

The input schema has 0% description coverage, so the description must compensate. The only parameter is 'domain', and the description does not add any formatting, input constraints, or examples beyond what the parameter name already implies. It adds no semantic value to the schema.

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 action ('Look up'), the resource ('domain registration data'), and specific data fields (registrar, dates, nameservers). It also identifies the method (via RDAP), which distinguishes it from sibling tools like dns_lookup or recon_subdomains.

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 (when domain registration data is needed) and the RDAP method implies a specific alternative to traditional whois. However, it does not explicitly name alternative tools or exclusions, so it stops short of a 5.

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