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 does reveal one useful behavior ('No browser is launched'), but it says nothing about whether a network request is made, timeouts, errors, authentication, side effects, or what result is returned. This is too thin for a tool with no annotation coverage.

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. The core purpose is front-loaded, and the key behavioral caveat follows immediately. 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?

The tool has 9 optional parameters, no output schema, and no annotations, yet the description only covers the general purpose and one behavioral constraint. It doesn't explain how the many 'discarded' parameters relate to the URL check, what a successful check looks like, or how to interpret failure. For an agent selecting and invoking this tool, this is incomplete.

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 schema covers 100% of parameter descriptions, so the baseline is 3. The description adds no parameter-level meaning beyond what the schema already provides, but it also doesn't need to because each parameter is documented. There is no added semantic value, but no gap either.

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 and resource: 'Check whether a URL can be opened.' The explicit 'No browser is launched' also helps distinguish it from browser-driven siblings like playwright-url-ok. However, it doesn't clarify what 'opened' means operationally (e.g., HTTP fetch, DNS resolution, status-code check), so it falls just short of a 5.

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 'No browser is launched' statement implies a when-not condition: use this when a lightweight URL availability check is sufficient and a real browser launch is not needed. But it never names alternatives or states explicit conditions for choosing this tool over normalize-url, fetch-status, or playwright-url-ok.

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