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

No annotations are provided, so the description carries the full burden. It only states that the tool does not include WHOIS or ownership data, which is a limited behavioral disclosure. It does not mention that only the 'host' parameter is used, that other parameters are discarded, or whether any network or disk access occurs. The schema descriptions mention 'discarded after the shape check' for several parameters, but this is not reflected in the tool description, leaving the agent unaware of side effects or output characteristics.

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, concise sentence that is front-loaded with the primary purpose. However, it omits essential context about the parameter set and usage constraints, making it under-specified rather than appropriately concise. It earns a middle score because it is efficient but incomplete.

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?

Given nine parameters, no output schema, and no annotations, the description is significantly incomplete. It does not explain what the tool does with all parameters, what the output format is, or how an agent should construct a valid call. The tool appears to be a multi-purpose shape checker, but the description narrows it to hostname splitting, leaving the agent without enough information to use it correctly for other parameter types.

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 already documented. The description adds minimal value beyond that; it reinforces that 'host' is a public hostname but does not clarify the role of the other eight parameters or that they are effectively ignored. With complete schema coverage, the baseline of 3 is appropriate, but the description fails to help the agent understand which parameter to actually supply.

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 (hostname). However, the input schema includes nine parameters (ref, url, city, feed, json, path, zone, query) that are not addressed by the description, making the tool's actual scope ambiguous and failing to distinguish it from siblings like figma-url-shape or github-repo-shape. The core purpose is clear but incomplete.

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?

No guidance is provided on when to use this tool versus alternatives, nor does it explain which of the nine parameters is relevant. The description implies hostname input but does not explicitly state that other parameters are ignored or how to select this tool over domain-related siblings. This leaves the agent without clear decision criteria.

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