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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose that no browser is launched, but it does not explain what 'check whether a URL can be opened' actually entails (e.g., does it perform a network request? does it validate format only?). The parameter descriptions hint that many inputs are 'discarded after the check,' but the tool description omits this behavior entirely, leaving the agent in the dark about side effects and semantics.

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—a single sentence—which is efficient in length. However, it is under-specified to the point of being unhelpful; conciseness here is not balanced with adequate information. There is no structure or front-loading of critical details beyond the caveat about no browser.

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?

This is a tool with nine optional parameters, no output schema, and no annotations. The description is far too thin: it does not explain return values, the relationship between parameters, when the tool is applicable, or any behavior beyond 'no browser.' Given the complexity, this is completely inadequate for an agent to call it 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 has 100% coverage with descriptions for all nine parameters, so the schema already documents each parameter's purpose. The tool description adds no additional context about the parameters, so it stays at the baseline 3. It does not help an agent understand how the parameters relate to the stated URL-checking purpose.

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 ('check whether a URL can be opened') and a disambiguating caveat ('No browser is launched'), but the input schema lists nine unrelated parameters (city, json, path, zone, query, etc.) that have nothing to do with URLs. The purpose is ambiguous and the description does not reconcile the stated scope with the actual parameter set, nor does it differentiate from siblings like normalize-url or fetch-status.

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 use this tool versus alternatives. The description offers no context about the intended use case, no exclusion conditions, and no mention of sibling tools such as playwright-url-ok or normalize-url. An agent cannot infer when this tool is the right choice.

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