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

No annotations are provided, so the description must disclose behavior. It only mentions hostname splitting and ignores the other input types. It does not state that inputs are discarded, that no disk access occurs for paths, or any side effects. The description is silent on nearly all behavioral aspects, making it severely inadequate.

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 one short sentence, which is concise, but it is so under-specified that it fails to convey the tool's true scope. While there is no wasted wording, the content is misleading and incomplete, so the efficiency is not helpful.

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?

With 9 parameters, no output schema, and no annotations, the description is grossly incomplete. It does not explain how the tool processes the various inputs, what 'shape' means for each type, or what output or behavior to expect. An agent cannot safely invoke this tool based on the given description.

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 descriptions cover each parameter fully, so the baseline is 3. However, the tool description actively misleads by implying only hostname is relevant, while the parameters include weather, JSON, paths, etc. This adds negative value and undermines the schema's clarity. It does not explain how the different parameters relate to the stated purpose.

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 claims the tool splits a hostname into labels, but the schema accepts 9 different parameter types including city, JSON, path, timezone, and query. This narrow purpose misrepresents the tool's actual scope, so an agent cannot correctly understand what the tool does. It does state a specific verb and resource, but the mismatch with the schema makes it misleading.

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 versus its many siblings (e.g., normalize-url, validate-json, geo-hint). The description offers no conditions or alternatives, leaving an agent without any basis to select it appropriately.

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