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

There are no annotations, so the description carries the full burden of behavioral disclosure. It does disclose a relevant behavior: no browser is launched, implying no visual or GUI side effects. However, it does not clarify whether the check makes a network request, whether it is read-only, or what the return value looks like.

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 consists of two short, front-loaded sentences with no filler. Both sentences add information: one states the core action, the other clarifies a critical behavioral boundary. This is appropriately sized and well structured.

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 8 parameters and no output schema or annotations, the description only provides a high-level intent. It does not indicate which parameter carries the URL, what result to expect (boolean, status, error), or how it relates to the seemingly unrelated parameters like city, feed, and json. An agent would need to make assumptions to invoke this tool 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?

The input schema provides descriptions for all 8 parameters, giving 100% schema description coverage. The tool description itself adds no parameter information, so the baseline of 3 applies. The schema descriptions do the heavy lifting here.

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.' It also includes a key differentiator, 'No browser is launched,' which separates it from sibling tools like playwright-url-ok that imply real browser activity. This is concise and immediately tells an agent what the tool is for.

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 gives an implicit usage hint via 'No browser is launched,' suggesting a lightweight check rather than full browser automation. However, it does not explicitly name alternatives or provide conditions for when to use this tool over fetch-status, web-fetch, or normalize-url. The guidance is present but not explicit.

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