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

With no annotations provided, the description carries the burden of disclosing behavior. It does state that no browser is launched, which is useful, but it omits other crucial behavior: whether network access occurs, what 'ok' means, what the return value looks like, and whether input is normalized or merely validated.

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 brief and front-loaded, with no filler or repetition. The two sentences each carry information: the primary purpose and a key behavioral clarification. However, it is somewhat too sparse given the tool's complexity and sibling context, so it does not reach a 5.

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 large sibling family and 9 optional parameters, the description needs to explain more about when to use this tool and what 'can be opened' means. It lacks any detail about return behavior, input relevance, or relationship to similar tools, so the tool definition is incomplete enough that an agent could easily misuse it.

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?

Schema description coverage is 100%, so the schema already documents all nine parameters. The tool description itself adds no additional parameter semantics, but per the baseline rule, when schema coverage is high, the description need not repeat schema details. A 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 states a specific action ('Check whether a URL can be opened') and adds a meaningful constraint ('No browser is launched'), which distinguishes it from browser-launching siblings like playwright-url-ok. It does not explicitly name sibling tools or the exact meaning of 'can be opened', but the core purpose is clear.

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 description gives no guidance on when to use this tool instead of alternatives such as normalize-url, fetch-status, or playwright-url-ok. It provides no exclusions, no prerequisites, and no context about URL types or expected inputs, so an agent would struggle to select it confidently.

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