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

No annotations are present, so the description carries the full burden of behavioral disclosure. It discloses only that no browser is launched, omitting whether a network request is made, what 'can be opened' actually checks, and what the result looks like.

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 two short sentences, front-loaded, and contains no filler; the no-browser qualifier earns its place. It is not a 5 because the brevity contributes to the ambiguity around what 'can be opened' means.

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 heterogeneous optional parameters and no output schema or annotations, this is incomplete: there is no return-value description, no network-behavior statement, and no relationship to the many URL siblings. An agent cannot confidently predict the tool's behavior or output.

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 coverage is 100%, so the baseline is 3. The tool description adds no parameter meaning and does not explain why non-URL parameters like city, feed, json, zone, and query are accepted, but the schema itself provides descriptive text for each parameter.

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 verb and resource ('check whether a URL can be opened') and adds a useful qualifier ('No browser is launched'), so it is not a tautology. However, 'can be opened' is ambiguous—it could mean syntactic validity, DNS resolution, or HTTP reachability—and it does not clearly distinguish this from fetch-status or normalize-url.

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?

The description provides no when-to-use guidance or alternative selection. The only contextual clue is that no browser is launched, which implicitly rules out browser-url-ok but fails to route the agent among multiple URL-related siblings like fetch-status, web-fetch, or normalize-url.

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