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

No annotations are provided, so the description carries the burden. It only mentions 'without WHOIS or ownership data', which hints at a non-network operation but does not disclose side effects (likely none), data handling, or behavior for the other parameter types. The schema notes 'discarded' for some fields, but that is in structured data, not the 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 concise sentence, but it is incomplete and under-specified for a tool with 9 heterogeneous parameters. Conciseness alone is not effective when it omits essential scope information.

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?

With 9 optional parameters and no output schema, the description provides almost no context. It does not explain what the tool returns, how each parameter is processed, or why it exists alongside similar shape-checking tools. An agent would be unable to use it correctly without opening the schema and inferring intent.

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%, giving baseline 3, but the description does not add meaning beyond the schema and actually conflicts by only referencing hostname. The description fails to explain how the other parameters map to the tool's behavior, so it does not compensate for the schema's terse per-field notes.

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 action for hostnames ('Split a hostname into labels') but the input schema accepts 9 unrelated parameters (ref, url, city, feed, host, json, path, zone, query), many of which are discarded after checks. The description does not represent the tool's actual scope, making it misleading for an agent deciding what this tool does.

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 on when to use this tool versus the many shape-specific siblings (github-repo-shape, jira-key-shape, figma-url-shape, etc.). The description gives no conditions, exclusions, or alternatives, so an agent cannot route correctly.

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