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

With no annotations, the description carries the full burden of behavioral disclosure. It only says no browser launch, which is useful, but it does not say whether it makes network requests, whether it is read-only, or what other side effects may occur. The schema-mandated effects like 'discarded after the shape check' are not surfaced in the description.

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: two sentences, each with a clear function. The first states the core action and the second adds the most important behavioral caveat. No wasted words.

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 9 optional parameters, no required parameters, no annotations, and no output schema, the agent is left without guidance on which inputs to pass. The description focuses on one behavior but fails to explain the broader shape-checking context or how to select among properties like city, json, path, zone, etc.

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%, and each parameter has its own description, so the description need not repeat parameter semantics. The description adds no meaning about the nine optional parameters, but it also doesn't need to, since the schema is already rich.

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') and adds a useful negative behavior ('No browser is launched'). This differentiates it somewhat from playwright-url-ok, though it doesn't explicitly describe how it differs from siblings 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?

There is no explicit guidance about when to use this tool versus alternatives. The 'No browser is launched' phrasing implies a quick or side-effect-free check, but the description gives no alternatives, prerequisites, or a not-to-use guidance.

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