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

No annotations are present, so the description carries the full burden. It does disclose some behavioral traits, such as not including WHOIS/ownership data, discarding certain parameters, and no disk access, but it leaves out return behavior, error cases, and potential network effects.

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. Every word contributes distinct meaning, and the parameter descriptions are reasonably compact.

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 annotations, no examples, and no error behavior. The description also fails to identify which optional parameter is the primary input or what the returned labels look like, leaving important operational context missing.

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?

All 9 parameters have schema descriptions, which meets the high-coverage baseline. However, the tool-level description does not connect most parameters to the stated hostname-splitting purpose; only 'host' is clearly relevant, while the others are described as discarded or unrelated.

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 and resource: 'Split a hostname into labels' and distinguishes itself by explicitly excluding WHOIS/ownership data. It is recognizable among sibling URL and shape tools, though it does not name them.

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 sibling tools such as normalize-url, figma-url-shape, or github-repo-shape. The phrase 'without WHOIS or ownership data' is a negative scope, not an actionable usage recommendation.

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