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

There are no annotations, and the description does not disclose side effects, return format, error behavior, or whether unrelated parameters are ignored. The mismatched parameter descriptions further obscure what the tool actually does. This leaves significant behavioral ambiguity.

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 concise and front-loaded with the main action. It avoids unnecessary words and is easy to scan. It loses one point because the exclusion clause 'without WHOIS or ownership data' is somewhat ambiguous without explaining why it is relevant.

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 no output schema and several seemingly irrelevant parameters, the description is incomplete. It does not explain what the tool returns, how inputs like 'url', 'json', or 'timezone' relate to hostname splitting, or what edge cases exist. The mismatched parameter metadata makes the tool especially hard to use correctly.

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?

The parameter descriptions are largely inconsistent with the tool purpose. 'url' mentions URL normalization, 'json' mentions JSON validation, and 'timezone' mentions IANA timezone names, none of which align with 'Split a hostname into labels.' Only 'host' is plausibly relevant, but the schema does not clarify the relationship between parameters.

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 a specific action ('Split a hostname into labels') and a resource. The phrase 'without WHOIS or ownership data' adds useful scope clarification. It is slightly less than 5 because it does not clarify what the output shape is.

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 description implies this tool is for hostname label splitting, not WHOIS or ownership lookup. However, it does not explicitly contrast with sibling tools like normalize-url or validate-json, nor does it state when this tool should be preferred. Some context exists but no direct usage guidance.

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