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

No annotations are provided, so the description carries the burden of explaining behavior. It does state that no WHOIS or ownership data is involved, implying no external lookup, but it does not explicitly mention side effects, data retention, or whether the operation is read-only.

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, focused sentence with no redundant words. It clearly states the core operation and an important limitation in a concise way.

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 nine optional parameters, no required parameters, and no output schema, the description is far too minimal. It does not specify which input to provide, what output format to expect, or how errors are handled, making the tool effectively unusable based solely on the description.

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?

The description mentions hostname, so 'host' is the only obviously relevant parameter, but the schema includes eight other optional parameters (ref, url, city, feed, json, path, zone, query) with unrelated or 'discarded' descriptions. The description does not clarify which parameters are actually needed, leaving invocation ambiguous.

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 gives a specific action and object: 'Split a hostname into labels', and scopes it with 'without WHOIS or ownership data'. However, the tool name 'domain-shape' suggests validation/shape-checking, which is not explicitly stated in the description.

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 description offers no guidance on when to use this tool versus alternatives like figma-url-shape, github-repo-shape, or normalize-url. The only hint is the negative phrase 'without WHOIS or ownership data', which does not explain when this tool should be selected.

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