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

With no annotations, the description carries the full burden of behavioral disclosure. It states a transformation and a data limitation, but does not say whether any I/O occurs, what the return value looks like, or how malformed inputs are handled. The schema notes that several fields are discarded, but the overall behavior remains underspecified.

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 sentence with no filler and front-loads the core operation. Its brevity is a conciseness strength, even though the under-specification hurts other dimensions.

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?

For a tool with 9 optional parameters, no output schema, and no annotations, this description leaves too much implicit: expected output, which parameter applies in which scenario, and error behavior. The schema partially compensates for parameter semantics, but the overall call contract is still incomplete.

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?

Schema coverage is 100%, with every parameter having its own description, so the baseline is met. The free-text description adds no parameter-level meaning beyond what the schema already provides. Some schema descriptions, like 'discarded after the shape check,' are actually more informative than the main description.

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?

Description uses a specific verb ('Split') and resource ('hostname'), and adds a useful negative scope ('without WHOIS or ownership data') that distinguishes it from lookup-style tools. However, the 9-field input schema suggests a broader set of inputs, so the stated purpose is clearer than the actual schema implies.

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 only usage guidance is the negative constraint 'without WHOIS or ownership data,' which tells an agent what the tool does not provide. It does not name sibling tools or state when to prefer domain-shape over normalize-url, file-path-ok, or related validity-checking tools. Usage context is implied but not explicit.

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