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

There are no annotations, so the description carries the burden of behavioral disclosure. It discloses that no browser is launched but does not state whether network requests are made, whether there are timeouts or side effects, what 'opened' means, or that several input parameters are discarded. This leaves important behavioral traits undisclosed.

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, purposeful sentences. The core action is front-loaded in the first sentence, and the key behavioral qualifier, 'No browser is launched,' is clearly separated in the second. There is no filler or repetition.

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?

With 9 parameters, no output schema, and no annotations, a one-sentence description is insufficient. It does not explain what the tool returns, which parameters are required for a meaningful call, or how the URL openability check is performed. The completeness is inadequate for safe and 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 tool description itself adds no parameter guidance, but the input schema has 100% description coverage, so the baseline is 3. The schema descriptions do add some context, though many note that values are 'discarded,' which does not clarify how the url parameter is actually used for 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?

The description states a specific verb and resource: 'Check whether a URL can be opened.' The qualifier 'No browser is launched' helps distinguish it from browser-driven siblings like playwright-url-ok. However, it does not define what 'can be opened' means in terms of HTTP status or URL shape, leaving some overlap with fetch-status and normalize-url.

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 a lightweight, non-browser check, which gives some usage context. However, it does not explicitly say when to prefer this tool over alternatives such as playwright-url-ok, web-fetch, or normalize-url, nor does it mention any exclusions or prerequisites.

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