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

With no annotations present, the description must supply behavioral context. It does disclose one key behavior: 'No browser is launched.' However, it does not explain what 'can be opened' means in practice—whether it performs a network request, checks syntax, validates HTTP status, or something else—leaving important behavior unspecified.

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 and front-loaded: the core purpose appears in the first sentence, and the key clarification appears in the second. It wastes no words, though the brevity leaves some needed context unaddressed.

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?

The tool has seven parameters, no annotations, no output schema, and several closely related siblings. A one-line purpose plus a caveat is not enough to guide an agent on which parameters to supply, what the check actually validates, what result to expect, or when to prefer this tool over nearby alternatives.

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 seven parameters, so schema coverage is high and the description need not repeat them. The description adds no meaning about which parameters to use for the URL openability check, and the schema itself contains several odd params like ref, city, and feed that seem unrelated to the stated purpose.

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 verb and resource: 'Check whether a URL can be opened.' It also adds the clarifier 'No browser is launched,' which helps distinguish it from a browser-based check. However, it does not explicitly name sibling tools like playwright-url-ok or web-fetch to draw the distinction.

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 for quick, non-browser URL checks, giving some usage context. But the description does not explicitly state when to use this tool versus alternatives such as playwright-url-ok, fetch-status, or web-fetch, nor does it mention any exclusions.

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