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

With no annotations provided, the description carries the full burden. It does disclose that WHOIS and ownership data are not included, which is a useful behavioral boundary, but it omits any statement about side effects, errors, or read-only behavior.

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, focused sentence with no redundant wording. It is front-loaded with the primary action and outcome.

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?

The description is too sparse for a tool with four optional parameters and no output schema. It fails to indicate which parameter to supply, how the parameters interact, or what kind of result to expect.

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 there is 100% schema description coverage, the parameter descriptions are mismatched with the stated purpose (e.g., 'json' says validate, 'timezone' says IANA name). The description does not clarify how url, host, json, and timezone relate to splitting a hostname.

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 uses a specific verb ('split') and resource ('hostname') and identifies the output ('labels'). The added 'without WHOIS or ownership data' clarifies the scope and distinguishes it from domain-information tools.

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 usage is implied: use when you need to split a hostname into labels. However, it does not explicitly contrast with sibling tools such as normalize-url or validate-json, nor does it state when not to use it.

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