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

With no annotations, the description must carry the full behavioral disclosure burden, but it only reveals that a browser is not launched. It does not state whether a network request is made, what 'ok' means, what gets returned, whether parameters are normalized, or whether there are any side effects. The schema's 'discarded' notes help, but they are structured field descriptions, not substitute behavioral context in the tool description.

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 very concise: two sentences, each carrying necessary information. The first sentence states the action, and the second reveals a key behavioral constraint. There is no fluff or repetition.

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 tool with nine parameters, no output schema, and no annotations, the description is too sparse. It does not explain the tool's return format, the meaning of an 'ok' result, the role of the many optional parameters, or how this tool relates to the sibling URL-checking tools. The schema covers parameters but not the operation-level context an agent needs.

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?

Schema description coverage is 100%, so the schema already documents all nine parameters. The tool description itself adds no parameter-level meaning, which is acceptable given the high coverage, but it also does not clarify which parameters are central to the URL check or how they interact.

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 names a specific action ('Check') and resource ('a URL'), and the 'No browser is launched' sentence helps separate it from a browser-based check. However, 'can be opened' is ambiguous—it could mean syntactic validity, HTTP reachability, or some other notion of openability—and the schema's 'discarded after the shape check' hints at a broader shape-validation behavior that the description does not mention.

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 about when to use this tool versus alternatives like browser-url-ok, fetch-status, or normalize-url. The only hint is the negative constraint 'No browser is launched,' which weakly implies a lightweight check but does not state prerequisites, exclusions, or selection criteria.

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