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

With no annotations provided, the description carries the burden of behavioral disclosure. It explicitly reveals that no browser is launched, which is an important side-effect guarantee. But it does not disclose whether the check involves a network request, whether it only validates URL shape, or what the 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?

Two short sentences with no filler. The core action is front-loaded and the key caveat about not launching a browser 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?

For a tool with 9 optional parameters, no annotations, and no output schema, the description is too sparse. It omits what success/failure looks like, how to choose which parameter to supply, and whether the check actually contacts the network. An agent cannot fully predict the tool's behavior from this definition alone.

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 description adds no parameter-level meaning, but the input schema already documents all nine parameters with 100% coverage, so the baseline of 3 applies. The description's singular 'a URL' does not clarify how the many non-URL parameters (city, feed, json, path, timezone, query, ref) relate to the check.

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?

States a clear action—checking whether a URL can be opened—and adds the key constraint 'No browser is launched,' which helps distinguish it from browser-url-ok. The meaning of 'opened' (syntax validation vs. actual reachability) is slightly ambiguous, so it doesn't earn 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 phrase 'No browser is launched' gives an implied usage signal: this is a lightweight alternative to browser-based checks. However, it never explicitly names alternatives like browser-url-ok, fetch-status, or web-fetch, nor does it state when to prefer one over the other.

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