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

No annotations are present, so the description carries the full burden of behavioral disclosure. It reveals only that no browser is launched. It does not clarify whether the tool performs a network request, what kind of check is executed, how errors or timeouts are handled, or what a positive/negative result looks like. The disclosed trait is true but insufficient.

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 exactly two short sentences, front-loaded with the core purpose and followed by a key constraint. There is no filler or redundancy; each sentence 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?

Given a tool with a ten-parameter schema and no output schema, the description is too sparse. It leaves unresolved why parameters like city, ref, or json are part of the schema, how the URL check relates to those params, and what the tool returns. An agent cannot confidently predict invocation behavior or output from this text 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?

All 10 parameters have individual descriptions in the schema, so schema coverage is 100%. The tool description itself contributes zero parameter-level meaning, but per the rubric the baseline is 3 when the schema already documents parameters. The schema descriptions themselves are odd (many say the value is discarded), yet that is schema information, not something the description needs to duplicate.

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 concrete verb and resource: 'Check whether a URL can be opened.' It also adds a differentiating constraint, 'No browser is launched,' which hints at sibling distinction. However, it does not define what 'can be opened' means (e.g. HTTP status, port accessibility) nor explicitly contrasts with more than the browser-launching sibling.

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 explicit statement about when to use this tool over alternatives like browser-url-ok, fetch-status, or web-fetch. The 'No browser is launched' note provides an implicit hint but not a clear decision rule or exclusion of other tools.

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