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

With no annotations, the description carries the transparency burden. It does disclose one relevant behavior: no browser is launched. However, it does not say what 'can be opened' means, whether a network request is made, whether it returns a boolean, or what the side effects would be. The disclosure is helpful but thin.

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 sentences with no filler. The core action is front-loaded, and the distinguishing negative behavior is stated immediately after the main purpose. Nothing in the description is wasted.

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 zero required parameters, nine optional parameters, no output schema, and no annotations. The description does not explain why the other eight parameters exist, which of them actually drive the check, or what the caller receives as a result. The schema helps with individual parameter intent but not with tool-level context.

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 has 100% description coverage, so the schema already does most of the parameter work. The description adds no extra parameter-level meaning, and the schema's `url` description says 'normalize or cite' rather than matching the tool's check-open behavior, leaving a small semantic gap.

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 note 'No browser is launched' helps separate it from the sibling `browser-url-ok` and browser-related tools. It does not name or explicitly contrast the sibling, but the scope is legible enough.

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 guidance on when to use this tool versus browser-url-ok, fetch-status, normalize-url, or web-fetch. 'No browser is launched' is a behavioral fact, not a usage recommendation. No conditions, prerequisites, or exclusions are provided.

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