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

With no annotations, the description carries the behavioral burden. It discloses one meaningful behavior, that no browser is launched, but it does not say whether an actual network request is made, what the return value is, or whether the URL must be reachable versus merely well-formed.

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 short sentences, with the primary action first and the key differentiator second. Every word earns its place; there is no filler 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 optional parameters and no output schema, the description is too thin. It does not define what 'can be opened' means, does not state the returned value (boolean/status/error), and does not explain how the many unrelated-looking parameters relate to the check.

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 covers all nine parameters with descriptions, so the baseline is 3 and the description does not need to repeat them. It adds no extra parameter meaning, but none is required because coverage is 100%.

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 operation ('Check whether a URL can be opened') on a specific resource (a URL). The added sentence 'No browser is launched.' immediately distinguishes it from browser-oriented siblings like browser-url-ok, so the core purpose is unambiguous.

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 explicit when-to-use or when-not-to-use guidance is given. The description does not name an alternative or state the condition for choosing this tool over browser-url-ok or fetch-status; 'No browser is launched' implies a lightweight check but leaves the usage decision to inference.

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