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

The description mentions 'without WHOIS or ownership data,' which hints at a non-networking operation, but it doesn't explain that all parameters are optional, that many values are discarded after a check, or what the actual return behavior is. The schema descriptions partially fill this in, but the description itself contributes little, and there are no annotations.

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 sentence is simple and front-loaded, but it is too short to give an accurate account of a tool with nine parameters and several likely sibling responsibilities. It reads more like an under-specification than a focused description.

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?

With nine parameters, a 100% schemed but no output schema or annotations, this one-line description leaves too much unknown about how to invoke the tool correctly. There is no mention of the general shape-check behavior that the parameters suggest, no output structure, and no disambiguation from siblings.

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 parameters are individually documented, but the description adds only the mention of hostname, implying that the tool works on hostnames alone. This is misleading for the other parameters like zone, query, json, etc., and the description does not help clarify how the many optional parameters relate to the tool's purpose.

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 says the tool splits a hostname into labels, which is a concrete operation, but the input schema has nine unrelated optional parameters (city, zone, query, json, etc.), so it doesn't convey the actual scope. It fails to differentiate from siblings like github-repo-shape or figma-url-shape, which evidently do specific shape checks.

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 alternatives. It doesn't mention normalize-url, browser-url-ok, or any sibling, nor does it state prerequisites or typical use cases.

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