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. It only states that no browser is launched, which gives a hint of side-effect-free behavior, but it does not mention return values, error conditions, whether it performs any mutations (despite 'discarded after' hints in parameter descriptions), or any other behavioral details. The cryptic parameter descriptions like 'discarded after the shape check' actually raise more questions than they answer.

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, consisting of a single sentence with no fluff or redundancy. It directly states the core action and a key caveat. There is no wasted wording, so it earns a perfect score on conciseness.

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 9 parameters and no output schema, yet the description provides almost no context to help an agent understand how these parameters relate to the tool's purpose. There is no explanation of what 'shape check' means, what the tool returns, how parameters like 'zone' or 'json' factor in, or what constitutes a successful 'opening.' The description is far too sparse for a tool of this complexity.

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 schema description coverage is 100%, the individual parameter descriptions are inconsistent with the tool's stated purpose. For example, 'url' is described as 'HTTPS URL to normalize or cite' rather than something about checking openability, and 'city' mentions a 'public weather hint' that seems unrelated. These descriptions add confusion rather than clarity, so they do not meaningfully compensate for the lack of a coherent parameter model.

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 clear verb and resource: 'Check whether a URL can be opened.' It also includes a notable negative ('No browser is launched') that hints at the tool's non-interactive nature. However, the list of parameters includes many unrelated fields (e.g., city, feed, zone), which muddies the purpose and makes it less immediately distinguishable from sibling tools like fetch-status or normalize-url.

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 provided on when to use this tool instead of alternatives. The description does not mention any conditions, contexts, or comparisons to sibling tools such as playwright-url-ok or fetch-status. An agent has no way to know if this is the right tool for a given scenario beyond the tool's name.

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