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

The only behavioral hint is 'without WHOIS or ownership data,' implying the tool does not perform network lookups. However, there are no annotations (e.g., readOnlyHint) and no other disclosure of side effects, error behavior, or output format. The mismatched schema descriptions also create misleading expectations about behavior.

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 that front-loads the primary action and resource. It avoids unnecessary fluff and is easy to read. However, the brevity is undermined by the overly verbose and irrelevant schema descriptions, though that is not counted against this specific dimension.

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 definition is incomplete and misleading due to the mismatched schema. The description does not explain how the parameters relate to splitting a hostname, and the parameter descriptions seem copied from other tools. This prevents the agent from understanding how to correctly invoke the tool, making the overall context inadequate.

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 schema parameters (url, host, json, timezone) have descriptions that are completely unrelated to the tool's stated purpose of splitting a hostname. For example, 'url' is described as 'HTTPS URL to normalize or cite' and 'json' as 'JSON text to validate; discarded after the check,' which are clearly not relevant to domain-shape. This makes the parameter semantics nonsensical and highly confusing.

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 clearly states the tool's primary action ('Split a hostname into labels') and resource (hostname), which is specific and unambiguous. The added qualifier 'without WHOIS or ownership data' helps set expectations, but the purpose could be slightly more precise regarding what constitutes 'labels'.

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 provides no guidance on when to use this tool compared to alternatives. It does not mention any conditions or scenarios where domain-shape is preferred over sibling tools like normalize-url or validate-json, leaving the agent without clear selection criteria.

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