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

No annotations are provided, so the description must carry behavioral disclosure. It states 'No browser is launched,' which is a useful trait, but it does not disclose side effects (e.g., network requests), permissions, rate limits, or what 'can be opened' means operationally. The schema hints at 'discarded after' for many parameters, but the description itself is silent on such behavior.

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 a single concise sentence, front-loading the core action ('Check whether a URL can be opened') followed by a clarifying note. There is no fluff or redundancy. However, it may be too terse given the tool's apparent complexity, but conciseness itself is well handled.

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?

With nine parameters, no annotations, and no output schema, the description is grossly inadequate. It does not explain the tool's full scope, return values, or when to use it. The single-sentence description fails to provide any context for the diverse parameters, making the tool nearly unusable for an agent without further investigation.

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 each parameter already has a meaning (e.g., 'Git ref name; discarded after the shape check'). The description adds nothing beyond that, so the baseline of 3 is appropriate. The parameters themselves are confusing given the URL-only description, but the schema does document them.

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 verb and resource ('Check whether a URL can be opened'), but the input schema includes nine unrelated parameters (ref, city, feed, json, zone, etc.), implying the tool handles far more than URLs. This mismatch makes the actual purpose ambiguous and potentially misleading, especially given sibling tools that focus on specific resource types.

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 siblings like playwright-url-ok, web-fetch, or fetch-status. The only differentiator is the phrase 'No browser is launched,' which hints at a non-browser check but does not explain when to choose this over alternatives or when not to use it.

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