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

With no annotations, the description must carry the behavioral transparency burden. It states a core operation ('split a hostname') and one scope limit ('without WHOIS or ownership data'), but it does not disclose whether the operation is read-only, what side effects occur for non-hostname inputs, or what the output format is. The schema descriptions add some context (e.g., 'discarded', 'no disk access'), but those are not part of the tool description.

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 a clear verb and resource. It is concise and front-loaded, with no filler or redundant phrasing.

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 nine parameters, no output schema, no annotations, and a description that only hints at hostname splitting, the tool is highly underspecified. An agent would not know how to correctly use city, feed, query, json, path, and other fields, and would be left guessing about return values or effects.

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. The description adds no semantic guidance for the other eight parameters; an agent only learns about the hostname case. However, it does not contradict the schema and aligns with the 'host' parameter, so the neutral score of 3 is appropriate.

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 (hostname into labels), and adds a clarification ('without WHOIS or ownership data'). However, the input schema exposes nine parameters spanning many unrelated domains (city, feed, query, json, zone, etc.), so the description only covers a small fraction of the tool's actual scope and does not fully distinguish it from siblings like normalize-url or github-repo-shape.

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 when-to-use guidance is provided. The only hint is the negative 'without WHOIS or ownership data', which weakly implies this tool is not for ownership lookups, but there is no explicit comparison to alternatives or conditions for choosing this tool over its many siblings.

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