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

With no annotations provided, the description carries the full behavioral burden. It discloses one trait (no browser is launched), but it does not explain whether a network request is made, what 'can be opened' means, what side effects or errors may occur, or what the result looks like. This is only minimal transparency.

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 two short sentences with no fluff. The core purpose is front-loaded, and the important behavioral note about not launching a browser is included efficiently.

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 optional parameters and no output schema, the description does not indicate which parameter is the primary URL, how parameters interact, or what the tool returns. This is too thin for an agent to confidently invoke the tool across the full range of possible inputs.

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?

Schema description coverage is 100%, so the parameters are already individually documented. The tool description adds no parameter-level meaning, but the schema descriptions cover the basics, so the baseline of 3 is appropriate.

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 uses a clear verb ('Check') and resource ('whether a URL can be opened'), and adds the meaningful qualifier 'No browser is launched.' This distinguishes it from browser-based alternatives, though it does not explicitly name a sibling or clarify whether the check is via HTTP, DNS, or URL syntax.

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 explicit guidance on when to use this tool versus siblings like fetch-status, browser-url-ok, or web-fetch. The 'No browser is launched' line hints at one exclusion, but it does not state when this tool should be preferred or what alternatives exist for other cases.

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