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

There are no annotations, so the description carries the full behavioral burden. It discloses that WHOIS/ownership data is not used, but it does not mention read-only behavior, discarded inputs (only schema notes imply discarding), return format, or failure behavior. This is thin for a tool with seven possible input parameters.

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 short sentence with no filler, and its key exclusion ('without WHOIS or ownership data') is clear. However, the brevity omits important context about the seven-parameter schema, so it is well-structured but overly compressed.

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?

Given the multi-parameter schema, missing annotations, and no output schema, a single sentence is not enough. The description omits the role of most parameters, what the labels output looks like, and how this tool relates to adjacent shape/validate tools. Schema notes partially compensate, but tool-level context is 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?

All schema properties have descriptions, so schema description coverage is high and the baseline is 3. The tool description does not explain which parameter to use or how url/city/feed/json/path relate to 'hostname', but the schema itself documents each property. Little parameter meaning is added beyond mapping 'hostname' to 'host'.

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 specific operation ('Split a hostname into labels') and a clear exclusion ('without WHOIS or ownership data'), so the core behavior is understandable. However, the input schema lists seven unrelated parameters (ref, url, city, feed, json, path) alongside host, and the description does not reconcile these with the hostname-splitting purpose, which leaves some scope ambiguity.

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 given about when to use this tool versus siblings like normalize-url, validate-json, file-path-ok, or other shape tools. The phrase 'without WHOIS or ownership data' hints that it is not a lookup, but it does not state prerequisites, exclusions, or alternative tool selection.

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