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 reveals that no browser is launched, which is useful, but it leaves ambiguous whether network access occurs, how 'can be opened' is determined, and why so many schema parameters are discarded. The description does not explain key runtime behavior.

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 the core purpose stated first and the important caveat second. There is no filler or redundancy. It is appropriately brief, though the brevity contributes to the lack of contextual completeness.

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 tool exposes 7 heterogeneous parameters, no required-field list, and no output schema, yet the description provides minimal orientation. It does not state which parameter is the URL to check, whether other parameters are optional compatibility shims, or what the caller receives back. The description is inadequate for an agent to confidently call this tool.

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 provides descriptions for all 7 parameters, so the baseline is 3. The tool description itself adds no parameter-level meaning. Furthermore, several schema parameter descriptions (e.g., ref, city, json) appear unrelated to URL checking, and the description fails to clarify how or whether they relate to the core 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 states a specific action and resource: 'Check whether a URL can be opened.' The addendum 'No browser is launched' distinguishes it from sibling tools like playwright-url-ok, giving it a clear identity. However, it does not fully separate it from normalize-url or web-fetch, which also operate on URLs.

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 description implies a lightweight, non-browser URL check, which gives context on when it might be used. But it never explicitly states when to prefer this tool over alternatives like web-fetch, normalize-url, or playwright-url-ok, nor does it mention exclusions or prerequisites.

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