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

There are no annotations, so the description carries the full burden. It only discloses that no browser is launched; it does not mention network requests, redirects, timeouts, side effects, or what counts as 'openable.'

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 a single sentence with no filler or redundant wording. It is maximally concise for the small amount of information it conveys.

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?

There is no output schema or annotation, and the description does not mention return values, expected inputs, error behavior, or the purpose of the many discarded schema fields. An agent lacks essential context for correct invocation and interpretation.

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 is highly misleading: most parameters are described as discarded or irrelevant, and the key 'url' parameter is described as 'HTTPS URL to normalize or cite' rather than a URL to check for openability. With no required parameters and additionalProperties false, an agent cannot reliably infer what to pass.

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 clearly identifies the action—checking whether a URL can be opened—and states an important constraint: no browser is launched. However, 'can be opened' is not precisely defined (e.g., HTTP 2xx, any response, or reachability), leaving some ambiguity.

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?

No guidance is given for when to use this tool versus siblings like fetch-status, normalize-url, or playwright-url-ok. The 'No browser is launched' note distinguishes it from a browser-based check, but it does not explain trade-offs or selection criteria.

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