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

The mention of 'without WHOIS or ownership data' hints at a parsing operation, but the schema's parameters are described as discarded or irrelevant (e.g., 'discarded after the length check'), and the actual behavior of splitting is not explained in terms of input/output.

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 succinct and to the point, using a short direct sentence that names the operation and its boundary (without WHOIS), which is efficient for a tool of this simplicity.

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?

There is no output schema, no mention of return format, and the tool is placed among diverse siblings without orientation, leaving the caller uncertain about what the tool actually produces or how to pass the hostname.

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?

Although the schema descriptions cover 100% of parameters, they are mostly unrelated to domain-splitting (e.g., city, feed, json) and include notes like 'discarded' or 'no disk access,' which actively misdirect rather than clarify the intended input.

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 clearly states the action (split a hostname into labels) and distinguishes it from WHOIS/ownership data, but it does not indicate which input parameter should be used for the hostname, leaving the purpose partially ambiguous.

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 siblings like normalize-url or browser-url-ok, and the schema with nine irrelevant parameters provides no contextual cues, making selection difficult.

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