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

With no annotations, the description bears full responsibility for disclosing behavior. It fails to mention that the tool likely performs a network request, what 'can be opened' means in practice, timeouts, or side effects. The statement 'No browser is launched' is the only behavioral detail and is insufficient.

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 only one sentence and is front-loaded, but it is not appropriately sized for a tool with nine parameters and no annotations. Its brevity omits critical information, making it under-specified rather than efficiently concise.

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?

Given the high parameter count and lack of output schema, the description is far too minimal. It does not explain how the parameters relate to the URL check, what a successful or failed check returns, or the tool's overall behavior. The description is inadequate for an agent to use the 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?

Although every parameter has a schema description, the descriptions are inconsistent with the tool's stated purpose. For example, 'url' is described as 'HTTPS URL to normalize or cite' rather than a URL to check, and many parameters are said to be 'discarded' without explaining their relevance. This adds confusion instead of meaning.

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 an action ('Check whether a URL can be opened') but does not clearly identify which parameter is the URL or how this differs from sibling tools like browser-url-ok or fetch-status. The presence of unrelated parameters such as 'ref', 'city', and 'zone' further muddles the tool's actual purpose.

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 given about when to choose this tool over alternatives like browser-url-ok or fetch-status. The only hint is 'No browser is launched,' which is a constraint but not a usage guideline.

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