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

No annotations are provided, so the description carries the full burden for behavioral disclosure. It states the core transform but does not describe return values, error behavior, handling of invalid hostnames, case sensitivity, or whether the TLD is included as a label. The 'without WHOIS or ownership data' clause adds some boundary context, but much remains undisclosed.

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, front-loaded sentence with no filler. It communicates the core action and an important limitation efficiently.

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?

Despite having 9 optional parameters and no output schema or annotations, the description does not clarify which parameter to pass, why the other parameters exist, how they relate to the tool's purpose, or what the result looks like. This leaves too much ambiguity for an agent to invoke the tool correctly in many contexts.

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 each parameter is individually documented in the schema. The tool description adds no parameter-level meaning and does not connect 'hostname' to the `host` parameter, but the schema already provides adequate descriptions for each field. The baseline of 3 is appropriate.

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, and it distinguishes itself by explicitly excluding WHOIS or ownership data. However, it does not explicitly name the `host` parameter or clarify which of the nine schema parameters are relevant to this action.

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 a weak implied boundary, but there is no explicit when-to-use guidance, no mention of alternatives among the many sibling tools, and no clarification of what to do if ownership data is needed. With nine optional parameters, the absence of usage direction is a significant gap.

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