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

Since no annotations are provided, the description carries the behavioral disclosure burden. It does disclose one meaningful behavior: no browser is launched. However, it does not state whether the URL is actually fetched over the network, what side effects might occur, or what the success/failure response looks like.

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 remarkably concise: two short sentences, no filler, and the most important behavioral constraint ('No browser is launched') is clearly stated. 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?

Despite having 9 optional parameters and no output schema, the description does not explain how the parameters relate to the URL check, which parameter should be provided, or what the tool returns. An agent would struggle to know how to invoke this tool confidently, especially with so many seemingly unrelated optional inputs.

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, with each parameter receiving its own specific description. The tool description itself adds no parameter-level meaning, but the schema already documents the parameters, so the baseline score of 3 is appropriate.

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 clearly states the tool's function with a specific verb and resource: 'Check whether a URL can be opened.' The additional phrase 'No browser is launched' helps differentiate it from browser-based alternatives like browser-url-ok, though it does not explicitly name any sibling tool.

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 phrase 'No browser is launched' implies the tool is appropriate when a browserless URL check is needed, but it does not explicitly state when to use this tool versus alternatives like browser-url-ok or fetch-status. Usage context is only implied, not directly explained.

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