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

With no annotations, the description carries the burden of disclosing side effects and boundaries. It only states that WHOIS/ownership data is not included, but does not mention network access, errors, output format, or side effects. Schema-level discard notes are not part of the tool description.

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 clear sentence with no unnecessary words or redundancy. It is concise and well structured for the small amount of information it conveys.

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 schema is complex with 9 optional parameters and no output schema, but the description is too sparse to make the tool fully self-explanatory. It does not specify which parameter to use, what the output looks like, or how the extra parameters relate to the stated purpose.

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?

Schema coverage is 100% and all parameters have descriptions, so the baseline is 3. The tool description adds no additional meaning beyond the 'host' parameter; it does not explain the purpose of the many other optional fields.

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 clear resource, with an explicit non-goal ('without WHOIS or ownership data'). However, it does not name any sibling tools or clarify why the schema exposes many unrelated optional parameters.

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 no guidance on when to use this tool versus alternatives such as normalize-url, file-path-ok, or other shape/ok tools. There is no mention of appropriate inputs or when not to use it.

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