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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It offers only one behavioral clue: no WHOIS or ownership data. It does not state whether the operation is purely local, whether unrelated parameters are discarded, what the return value looks like, or what happens when no valid hostname is supplied. This is insufficient for safe invocation.

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; the core verb and the key negative constraint are front-loaded. It is efficient, though its brevity is more a result of under-specification than of disciplined conciseness.

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?

Given 9 parameters, no annotations, and no output schema, this one-sentence description is not complete enough. It does not explain what the returned labels look like, how to choose among the many parameters, whether non-host parameters are discarded, or what the tool does when multiple or no parameters are provided. The schema provides some parameter-level detail, but tool-level invocation context is missing.

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?

All 9 parameters have descriptions in the input schema, so the baseline is 3. The tool description itself adds no parameter-level meaning and does not indicate that 'host' is the relevant parameter for this tool while the other eight are likely irrelevant or discarded. It therefore fails to bridge the mismatch between the singular 'hostname' in the description and the broad 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 states a concrete verb ('Split'), a resource ('hostname'), and an output ('labels'), so an agent can tell the core operation. The phrase 'without WHOIS or ownership data' also distinguishes it from ownership-oriented domain tools. However, the input schema exposes nine unrelated parameters, and the description does not name any sibling tools, so the overall purpose is clear but not fully differentiated.

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?

Usage context is only implied. The negative clause 'without WHOIS or ownership data' hints that this is the pure-shape choice when ownership details are not needed, but it does not explicitly state when to use this tool versus alternatives like github-repo-shape, figma-url-shape, or jira-key-shape. There are no when-not conditions beyond the ownership exclusion.

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