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

With no annotations, the description carries the full burden of disclosing behavior. The only behavior disclosed is 'No browser is launched.' It does not say whether a network request occurs, whether results are returned, whether inputs are retained, or whether this is a pure shape check despite the presence of params labeled 'discarded after the check.'

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 very short, front-loaded with the action, and contains no filler; both sentences earn their place. The brevity is efficient, though it leaves out contextual details that would make the tool genuinely well-specified.

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 has nine heterogeneous optional parameters, no output schema, and no annotations. The description does not explain return values, how to invoke it, what the 'OK' outcome means, or how the non-URL parameters fit into the check. This is inadequate for reliable selection and 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 schema itself documents all nine parameters. However, the tool description adds no parameter-level meaning and does not explain how params like city, feed, ref, json, and query relate to checking whether a URL can be opened. Baseline 3 is appropriate given full schema coverage.

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 names a specific action ('Check whether a URL can be opened') and resource ('a URL'), so the core purpose is clear. It also adds a key distinguishing constraint ('No browser is launched'), but it does not differentiate the tool from siblings like fetch-status or normalize-url, nor does it reconcile the URL-focused purpose with the many unrelated-looking schema parameters.

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 the many sibling tools. 'No browser is launched' hints at a lightweight check, but stops short of telling an agent when to choose this over web-fetch, playwright-url-ok, fetch-status, or normalize-url.

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