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

No annotations are provided, so the description must disclose side effects and read-only behavior itself. It only says 'without WHOIS or ownership data'; individual parameter descriptions mention 'discarded' and 'no disk access', but overall behavior, error cases, and output structure remain unspecified.

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, direct sentence with no wasted words. The qualifier 'without WHOIS or ownership data' is concise and adds meaningful differentiation.

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 tool with 9 optional parameters, no required fields, no output schema, and no annotations, the description omits essential context: which parameter is the hostname, what the returned labels look like, how invalid inputs are handled, and why the unrelated parameters exist.

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?

Although schema descriptions cover 100% of parameters, most of them (ref, city, feed, json, path, zone, query) appear unrelated to the stated hostname-splitting purpose and seem copied from other tool domains. Only 'host' clearly aligns with the tool description.

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 and resource: 'Split a hostname into labels.' The exclusion of WHOIS/ownership data helps differentiate the tool from lookup-style tools, though it does not explain the output format or how to handle the many unrelated schema fields.

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 sibling tools such as normalize-url or github-repo-shape, and no explanation of which of the nine optional parameters should be provided. The only usage hint is the negative clause about WHOIS and ownership data.

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