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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions that WHOIS/ownership data is not fetched, which is a positive note. However, it does not state whether the tool is read-only, what side effects (if any) occur, what the return value looks like, or how it handles the other input parameters. The behavioral information is minimal and insufficient for a tool with such a broad schema.

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 that immediately states the action and a key limitation. It is front-loaded, contains no filler, and is appropriately sized for a simple tool. Efficiency is optimal.

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?

Despite having 9 parameters, no output schema, and no annotations, the description only addresses hostname splitting. It does not explain why the tool accepts a city, feed, JSON, path, zone, or query, nor does it describe expected output or error behavior. This is a significant gap for an agent to correctly invoke the tool with the right parameters and interpret results.

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 100% coverage, meaning every parameter is described in the schema itself. The tool description adds no additional parameter-level meaning. Since the schema already documents all parameters, a baseline score of 3 is appropriate; the description does not need to repeat that but also does not add anything extra.

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 verb and resource: 'Split a hostname into labels'. It also distinguishes from WHOIS/ownership data, which helps differentiate from tools that might provide that. However, the input schema includes many unrelated parameters (city, feed, json, path, zone, query), so the description does not explain why those exist or how they relate to the core function, creating ambiguity 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?

The phrase 'without WHOIS or ownership data' implies a condition for use—when you only need label splitting and not ownership info. But it does not explicitly name any sibling tools (e.g., github-repo-shape, jira-key-shape) or state when to choose this over them. It provides a hint but not clear exclusion criteria.

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