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

No annotations are provided, so the description carries the full behavioral burden. It only discloses the lack of WHOIS/ownership data; it does not state output format, validation rules, side effects, or what happens with the many other accepted parameters. The schema notes that several fields are 'discarded,' but the description itself provides almost no behavioral context.

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 efficient sentence with the core action front-loaded and no filler. It is concise, though arguably too terse given the mismatch between the narrow description and the broad 9-parameter schema.

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 annotations, no output schema, and a description that only mentions hostnames, this is severely incomplete. An agent cannot determine which parameters are relevant, what the return value looks like, or how to invoke the tool correctly for the other schema fields.

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 description coverage is 100%, so the baseline is 3 even without parameter details in the description. The description adds no meaning beyond the word 'hostname' and does not clarify how 'host' relates to the split or why url, city, feed, json, path, zone, and query are accepted.

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'), a resource ('hostname'), and an outcome ('into labels'), and explicitly excludes WHOIS/ownership data, which helps distinguish it from ownership-related or other shape tools. However, the input schema lists eight other unrelated parameters with no explanation of their role, creating ambiguity about the tool's actual scope.

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 phrase 'without WHOIS or ownership data' implies this tool is for pure hostname lexical shape checks, not ownership lookups. But there is no explicit when-to-use/when-not-to-use guidance and no pointer to sibling tools such as github-repo-shape or file-path-ok, leaving the routing decision mostly to inference.

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