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 the tool avoids WHOIS/ownership data; it does not state whether inputs are validated, what happens to the many discarded fields, whether there are side effects, or what the output shape looks like. The schema descriptions mention 'discarded' behavior, but the main description itself is behaviorally thin.

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, front-loaded sentence with no filler. It states the core operation and one key limitation efficiently. It could add more context, but as a concise statement of purpose it earns its place.

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?

This tool has 9 optional parameters, no required fields, no output schema, and no annotations, yet the description only addresses hostname splitting. An agent cannot determine what the other parameters do, whether they are valid inputs for this tool, what the tool returns, or how to invoke it correctly for anything beyond a simple hostname. This is a serious completeness gap.

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 description coverage is 100%, so the baseline is 3 even with no parameter detail in the description. Each parameter has a meaningful explanation in the schema. However, the main description does not help reconcile why 'domain-shape' accepts city, feed, json, path, zone, and query in addition to host, leaving the mapping between purpose and parameters 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 uses a specific verb and resource: 'Split a hostname into labels' and adds a clear exclusion, 'without WHOIS or ownership data.' This distinguishes it from ownership-oriented domain tools and from sibling shape tools like github-repo-shape or jira-key-shape. However, it does not acknowledge the 9-parameter schema, which includes many unrelated fields, so the stated purpose feels narrower than the actual input surface.

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 explicit guidance on when to use this tool versus alternatives such as normalize-url, browser-url-ok, or github-repo-shape. The phrase 'without WHOIS or ownership data' implies a non-ownership use case, but it does not state when the tool is appropriate, what prerequisites exist, or which sibling tools should be used instead.

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