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, and it does add the useful detail that no browser is launched. However, it does not disclose whether the tool performs an HTTP request, what 'ok' means, whether side effects or network access occur, or what a 'safe shape check' involves. This is a minimal but not complete behavioral picture for a tool with no annotations.

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 sentences with no wasted wording, showing respect for brevity. Yet, given the tool has a 9-parameter schema, no output schema, and a large sibling set, the description is under-expressive rather than appropriately concise. It is not flabby, but it fails to carry enough informational weight for the tool's complexity.

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 9-parameter tool without output schema, without annotations, and with 27 sibling tools, the description is far too brief to fully contextualize it. It doesn't explain what 'can be opened' means as a return value, how to choose the relevant URL parameter, or when to use this rather than normalize-url or fetch-status. The absence of any output schema makes this gap more serious.

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 input schema description has 100% coverage, so each parameter is individually described, setting the baseline at 3. The overall description does not add any cross-parameter meaning, such as how the URL parameter interacts with the other nine fields or which parameter is primary. The schema itself does the heavy lifting, so no compensation is needed beyond the baseline.

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', so an agent knows this is a URL liveness/reachability check. The second sentence, 'No browser is launched', distinguishes it from browser-launching siblings like playwright-url-ok, though it does not name its full sibling context. However, the 9-parameter schema includes clearly unrelated fields (city, zone, json), and the description does not acknowledge these, which creates some ambiguity about the tool's full scope.

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?

There is no guidance on when to use this tool instead of the many siblings such as fetch-status, normalize-url, playwright-url-ok, or web-fetch. The phrase 'No browser launched' hints at a use case, but it is a behavioral note rather than a routing instruction. The agent is left to guess when this tool is preferable to `normalize-url` or `fetch-status`.

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