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

With no annotations, the description carries the burden and it does add one useful behavioral trait: it does not perform WHOIS/ownership lookups, implying a lightweight local operation. But it does not disclose behavior when multiple parameters are supplied, how invalid hostnames are handled, or what shape the returned labels take.

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 one short, front-loaded sentence. It contains no filler or redundancy and gets immediately to the action and scope.

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 not simple: it exposes nine optional parameters, has no output schema, and has no annotations. The description is too thin to let an agent confidently call it correctly, especially because it never explains whether only one parameter should be used, what precedence exists, or exactly what output to expect.

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 at 100% coverage, so the baseline applies. The description only reinforces that 'host' is the hostname-related input and does not add clarity about how the other optional fields relate to a hostname split.

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 names a specific action and resource: split a hostname into labels, and it clarifies scope by saying 'without WHOIS or ownership data.' It is clear on its own, though it never names sibling tools and the schema contains many unrelated optional fields that muddy which input is actually meant.

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 phrase 'without WHOIS or ownership data' gives an implicit when-not-to-use signal: use this for pure hostname shape, not registration or ownership lookups. However, there is no explicit guidance about when to choose domain-shape over sibling tools or how to select among the nine optional parameters.

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