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

With no annotations provided, the description carries the full burden of behavioral disclosure. It usefully declares that no browser is launched, which is a meaningful side-effect statement. However, it fails to disclose whether a network request is made, what the return value means, or how the check behaves when a URL is unreachable.

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 filler, front-loading the core action first. 'Check whether a URL can be opened. No browser is launched.' is efficiently packaged and 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?

Given the tool has 9 optional parameters, no output schema, and no annotations, this minimal description leaves critical gaps. The agent does not know what the tool returns, what the unrelated optional parameters do, or what prerequisites exist (e.g., URL format, network access). Such a sparse definition is not enough for correct invocation.

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% description coverage for all 9 parameters, so the baseline is 3. The tool description does not add any additional meaning beyond naming the URL check itself; it does not clarify the role of the other eight parameters or any constraints on the URL value. Therefore, it neither harms nor greatly enriches the schema descriptions.

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 resource (a URL), which is clear and distinct from a mere tautology. However, it does not differentiate from sibling tools like 'browser-url-ok' or 'web-fetch', so an agent cannot infer which sibling to choose without further context.

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 given about when to use this tool versus alternatives. The phrase 'No browser is launched' hints at a selection criterion but does not name sibling tools or provide explicit conditions. An agent is left to infer the appropriate usage context.

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