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

With no annotations, the description carries the full burden and only discloses that no browser is launched. It does not state whether a network request is made, what side effects occur, what 'opened' means, or what the return value/error behavior 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?

The description is a single, front-loaded sentence with no redundant words. It delivers the core action and an important behavioral caveat efficiently.

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?

Despite the short description, the context is incomplete: there is no output schema, no required parameters, and no explanation of how to invoke the check among nine optional inputs. The schema and description leave too many gaps for reliable use.

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?

Every parameter has a schema description, but those descriptions (e.g., 'Git ref name; discarded after the shape check', 'City name for a public weather hint') are inconsistent with the URL-checking purpose and the tool description adds no relationship between the nine optional parameters. The agent is left unsure which fields are relevant or how they combine.

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 action ('check whether a URL can be opened') and a constraint ('No browser is launched'), but 'can be opened' is ambiguous and the 9-property schema includes many unrelated fields (ref, city, feed, json, zone, query) that are not explained by this purpose. As a result, an agent cannot confidently determine what this tool actually does.

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 about when to use this tool instead of closely related siblings such as browser-url-ok, fetch-status, normalize-url, or domain-shape. The only hint is 'No browser is launched,' which is not enough to select between alternatives.

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