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

With no annotations, the description carries the full burden of explaining behavior. It mentions splitting a hostname and that WHOIS/ownership data is not involved, but does not clarify side effects, output format, or error behavior; several parameter descriptions mention 'discarded' but the overall behavior remains opaque.

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 concise sentence with no fluff or repetition. It is efficiently structured, though it could benefit from additional key details without becoming verbose.

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 tool has a complex schema with nine optional parameters and no output schema, yet the description provides minimal context. It does not explain expected input selection, return value, or examples, leaving the agent under-informed for reliable invocation.

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 schema descriptions cover all parameters, but many are unrelated to the stated purpose of splitting a hostname. The tool description adds no clarification about which parameters are relevant, and the contradictory breadth (URL, city, JSON, timezone, etc.) makes parameter semantics confusing.

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 clear operation, 'Split a hostname into labels', which identifies the core action and resource. However, it does not clearly distinguish this from sibling tools, and the broad optional schema with unrelated parameters weakens the clarity.

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 is provided on when to use this tool versus alternatives. The description does not mention use cases, exclusions, or relationships to sibling tools like normalize-url or browser-url-ok.

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