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

The description usefully discloses that no WHOIS or ownership lookup is performed and implies a pure transformation. However, with no annotations and no output schema, it does not explain what the returned labels look like, how errors are handled, or what happens when one of the other eight accepted schema properties is supplied.

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 with no filler, front-loading the verb and object. It is concise and readable, though slightly too short relative to the breadth of the input schema.

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?

With nine optional parameters, no annotations, and no output schema, the description is not complete enough. It does not identify which parameter is the primary input, whether the other parameters are ignored, or what form the label output takes.

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 already documents all nine parameters, so the baseline is 3. The description adds meaning only for the hostname concept, and it does not clarify how the other accepted parameters relate to this tool, leaving potential ambiguity.

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 states a specific action ('Split a hostname into labels') and a meaningful exclusion ('without WHOIS or ownership data'). It is clear about the tool's domain, though it does not explicitly differentiate from the many sibling shape/validation tools.

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?

There is no guidance on when to use this tool versus alternatives such as normalize-url, fetch-status, or the other shape tools. The only hint is the negative constraint about WHOIS/ownership, which does not help an agent choose among the sibling tools.

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