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

With no annotations present, the description carries the full burden of behavioral disclosure, yet it only states the core split operation. It does not reveal return format, handling of invalid hostnames, case/IDN normalization, or whether any network/disk access occurs; 'without WHOIS' is the only behavioral boundary.

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 front-loaded sentence with no filler, and both parts ('split a hostname' and 'without WHOIS/ownership data') carry meaning. It is appropriately terse but not padded.

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?

Despite a clear one-line purpose, the definition is incomplete relative to its context: no output schema exists, so return shape is not explained; there are 9 optional parameters and the description does not state that only `host` is relevant; and error/edge-case behavior is absent. An agent could guess the input but not the result contract.

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%, so param semantics are already fully documented in the schema. The description adds only the clue that 'hostname' maps to the `host` parameter; it does not add format details beyond the schema, keeping this at the high-coverage baseline.

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 names a specific verb ('Split') and resource ('a hostname'), and the phrase 'without WHOIS or ownership data' clarifies it is a syntactic shape utility rather than an ownership lookup. It does not explicitly name a sibling tool, so it stops short of full differentiation, but the intended operation is unmistakable.

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?

There is no statement of when to prefer this over alternatives, nor any named sibling or excluded alternative. The 'without WHOIS or ownership data' clause hints at a non-usage, but no explicit when-to-use guidance or routing to another tool is provided.

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