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

With no annotations provided, the description carries the full burden of disclosing behavior. It mentions 'split a hostname into labels' and notes the absence of WHOIS/ownership data, but it does not describe side effects, error handling, rate limits, or what happens with the other parameters. The description is too sparse to convey a complete behavioral picture.

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 concise, with a single sentence, but it is under-specified for a tool with nine parameters. While front-loading the core action is good, the brevity sacrifices necessary detail about the parameter scope, making it less helpful than it could be.

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 the complexity of nine optional parameters, no annotations, and no output schema, the description is severely incomplete. It only explains one aspect (hostname splitting) and leaves the purpose and behavior of the other parameters entirely unexplained. An agent cannot reliably determine what inputs are expected or what the tool does with them.

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 provides 100% description coverage for all nine parameters, so the baseline is 3. However, the tool description does not clarify how these parameters relate to the stated purpose (splitting a hostname). It adds no extra meaning beyond what the schema already states, and the connection between the 'host' parameter and the others is unclear.

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 verb and resource ('split a hostname into labels'), which is clear for the 'host' parameter, but it fails to address the other eight parameters that suggest a broader, multi-purpose tool. The name 'domain-shape' hints at domain processing, but the mismatch between the narrow description and the diverse parameter set creates confusion about the tool's actual scope.

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 is provided on when to use this tool versus its many siblings (e.g., github-repo-shape, figma-url-shape, jira-key-shape). The description does not mention any conditions, alternatives, or exclusions, leaving the agent to infer the tool's purpose from context alone.

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