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

The description discloses that 'Page content is not stored', which addresses a potential side effect. However, it does not clarify that most input parameters (e.g., 'city', 'feed') appear to be ignored or are decoys, nor does it mention that an HTTP request is made to obtain the status. This omission obscures important behavioral details.

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 front-loads the core function. It avoids unnecessary details and is grammatically efficient, achieving maximum clarity with minimal words.

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 description omits critical context: what happens with the optional parameters, the exact output format (beyond the three fields), error behavior, and whether the tool performs network requests. With nine optional parameters and no required ones, this lack of detail leaves significant gaps for an agent to call it correctly.

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?

Although the schema includes descriptions for all parameters, those descriptions are generic and mostly unrelated to the stated purpose (e.g., 'City name for a public weather hint'). The tool description does not reconcile these parameters with its actual functionality, making the parameter meanings misleading rather than informative.

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 primary function: 'Return host, scheme, and HTTP status for a URL.' This is specific and identifiable. However, the presence of nine unrelated optional parameters (e.g., 'city', 'zone', 'json') creates ambiguity about the tool's actual scope, preventing a perfect score.

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., 'normalize-url', 'fetch-status', 'domain-shape'). The description does not mention alternative tools or conditions for selection, leaving the agent to infer usage context.

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