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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only reveals that WHOIS/ownership data is not included; it does not describe output format, normalization behavior, side effects, error cases, or what happens with invalid hostnames. The schema field descriptions mention 'discarded' data, but the tool description itself is underspecified.

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 no filler: 'Split a hostname into labels without WHOIS or ownership data.' It front-loads the main action and resource, and every word contributes meaning.

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?

The tool has no annotations and no output schema, so the description should cover expected return values and invocation context. It does not explain what the split labels look like, whether all parameters are required or optional, or why several unrelated parameters appear in the schema. This is insufficient for an agent to confidently call the tool.

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 input schema has descriptions for all seven parameters, so schema coverage is effectively 100%, giving a baseline of 3. The description adds no parameter-level meaning beyond what the schema already provides, nor does it reconcile why a domain-shape tool accepts city, feed, json, ref, or path inputs.

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 uses a specific verb and resource: 'Split a hostname into labels.' It also clearly distinguishes this from ownership/WHOIS lookups, and the 'domain-shape' name makes the target resource obvious relative to sibling shape tools. However, it does not explicitly name sibling alternatives or draw a contrast with them.

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?

There is no guidance on when to use this tool over sibling shape tools such as figma-url-shape, github-repo-shape, or jira-key-shape. The phrase 'without WHOIS or ownership data' is a negative boundary, not a positive usage condition or an explicit exclusion with alternatives.

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