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

With no annotations, the description carries the full burden. It usefully discloses that no browser is launched, which is non-obvious given the playwright name. However, it does not say whether a network request is made, whether the check is purely syntactic, what side effects occur, or what the result format is.

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 critical 'No browser is launched' caveat is included immediately without redundant wording.

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 parameters, no output schema, and no annotations, so the description must explain far more than it does. It fails to define what 'can be opened' means, what the returned value indicates, when to use this over siblings, and how the many optional parameters interact with the check.

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 9 parameters. The description adds little parameter meaning beyond identifying 'url' as the central resource and implying the other parameters are secondary or ignored.

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 clear verb and resource: 'Check whether a URL can be opened.' The added 'No browser is launched' helps distinguish it from browser-url-ok, but 'can be opened' is still somewhat generic and could imply either reachability, syntax validity, or HTTP success.

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 statement implies a contrast with browser-url-ok, but the description never explicitly says when to use this tool versus alternatives like fetch-status, normalize-url, or browser-url-ok. Usage context is only implied, not stated.

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