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

There are no annotations, so the description carries the full burden of behavioral disclosure. It reveals one important trait, that no browser is launched, but does not explain what the check actually does, whether it makes network requests, whether it is read-only, or what it returns. The schema mentions discarded inputs, but the description itself remains thin.

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: the first states the purpose and the second adds a critical limitation. Every word earns its place, and the most important caveat is front-loaded.

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 a complex eight-parameter schema and no output schema or annotations, the description only addresses the URL check. It does not specify the return value, how the other parameters relate to the check, or when this tool should be preferred among the many similar sibling tools. The description is too thin for the tool's actual complexity.

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 provides descriptions for all eight parameters, and the tool description adds no parameter-level meaning. With high schema coverage, the baseline of 3 is appropriate; the description's singular 'URL' focus sits awkwardly with parameters like json and city, but those are explained in the schema.

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 specific action, 'Check whether a URL can be opened,' and adds a key differentiator: 'No browser is launched,' which helps separate it from the sibling browser-url-ok. It is clear, though it frames the tool as URL-only while the schema accepts eight varied inputs, so it is not fully precise.

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 phrase 'No browser is launched' implies this is the lightweight choice when a real browser session is undesirable, but it never names alternatives such as browser-url-ok or fetch-status, nor does it state explicit conditions for choosing this tool. The guidance is implied rather than explicit.

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