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

The description explicitly says it operates 'without WHOIS or ownership data', which helps set expectations about non-invasive behavior. However, it does not mention side effects, read-only guarantees, or error behavior, and there are no annotations to fill that gap.

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 one concise sentence with no filler, redundant phrasing, or unnecessary details. It front-loads the action and object clearly.

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 lacks output format, parameter usage guidance, and any practical invocation context. With nine optional parameters and no output schema, an agent would struggle to call this tool correctly based on the description alone.

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 description only discusses splitting a hostname, but the schema lists nine unrelated optional parameters such as city, feed, json, and zone. The parameter names and schema descriptions are not mapped to the described behavior, leaving the agent uncertain which parameters are relevant.

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?

States a specific verb 'split' and a specific resource 'hostname into labels', and clarifies scope by excluding WHOIS/ownership data. It does not mention the return format, but the core purpose is clear.

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?

No guidance on when to use this tool versus sibling tools such as normalize-url or browser-url-ok. The description gives no conditions, alternatives, or usage context beyond the basic operation.

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