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

With no annotations provided, the description must carry behavioral information. It does disclose the key side-effect boundary: no browser is launched. But it does not explain whether a network request is made, whether the check is purely syntactic, what the return value indicates, or how the many 'discarded' parameters behave beyond what the schema already says.

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 two short sentences with no wasted words. The primary action is front-loaded, and the important side-effect qualifier 'No browser is launched' is placed immediately after. Every word earns its place.

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?

For a tool with 9 parameters, no output schema, and no annotations, this description is too thin. It does not clarify the relationship between the URL-focused description and the non-URL parameters, nor does it explain expected return values or failure semantics. An agent would need to infer too much before calling this tool confidently.

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 input schema already documents each parameter thoroughly. The description adds no information about parameters, which is acceptable given the high coverage. However, the singular focus on 'URL' does not help the agent understand how non-URL parameters like json, city, or ref relate to the tool's 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 clearly identifies the resource. The added 'No browser is launched' also distinguishes it from sibling tools like playwright-url-ok that likely launch a browser. It loses a point because 'can be opened' is somewhat ambiguous and the input schema contains many non-URL parameters such as json, city, and ref.

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?

The description provides clear context for when to use this tool: when you only need to know whether a URL can be opened without actually launching a browser. This separates it from alternatives like playwright-url-ok or web-fetch. However, it does not explicitly name alternatives or state when not to use this tool, so it is one step below fully explicit guidance.

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