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

With no annotations, the description carries the burden of behavioral disclosure. It does add one meaningful trait: 'No browser is launched.' However, it does not explain whether any network request occurs, whether the check is purely syntactic, what side effects might happen, or what 'can be opened' actually entails.

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 extremely concise: two short sentences with no filler. The main purpose is front-loaded, and the critical caveat about no browser launch is placed immediately after the purpose.

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 leaves important context missing. It does not explain what the return value looks like (and there is no output schema), which of the nine optional parameters should be provided, or what 'can be opened' means in practice. Given the unusual set of parameters and the lack of output schema, this is not complete enough for confident invocation.

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 well documented. The tool description adds no parameter-level meaning, but the schema descriptions are rich enough that 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?

Description states a clear action ('Check whether a URL can be opened') and a useful caveat ('No browser is launched'), which partially distinguishes it from sibling tools like browser-url-ok. However, 'can be opened' is somewhat ambiguous—it could mean syntactic validity, reachability, or something else—and no sibling is explicitly named.

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 choose this tool over alternatives, no exclusions, and no mention of prerequisites. The 'No browser is launched' statement hints at a lightweight check, but it does not explicitly tell an agent when to use this vs browser-url-ok, fetch-status, or web-fetch.

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