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

No annotations are provided, so the description carries full burden. It discloses the core split action and the non-goal of WHOIS/ownership, but it doesn't say which of the 9 parameters is actually used, whether the others are silently ignored, whether any network/disk access occurs, or what happens for malformed hostnames. The schema's per-parameter discard notes are partially helpful but not enough.

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?

A single front-loaded sentence with no filler; the key action is first, and the no-WHOIS clarification is the only necessary qualifier.

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 annotations, and no output schema, the description is too thin. It doesn't specify input selection, return shape (e.g., list of labels), or edge-case behavior, so an agent can't fully predict invocation results.

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 description coverage is 100%, so the baseline is 3; the description adds only a loose association between 'hostname' and the `host` parameter. It doesn't help an agent decide whether to pass `url`, `path`, `json`, or other fields, since those are absent from the 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 operation ('Split a hostname into labels') and a clear exclusion ('without WHOIS or ownership data'), which distinguishes it from ownership-lookup and URL-normalization siblings. However, it doesn't acknowledge the 9-field input schema, so the purpose is clear in isolation but slightly mismatched with the accepted 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 implies the tool should be used when an agent needs dot-separated hostname labels and should not expect ownership data. It names no alternatives or explicit when-not conditions, so routing among sibling shape and URL tools is left to inference.

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