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

With no annotations present, the description carries the full burden of behavioral disclosure. It discloses that no browser is launched, which is useful, but it fails to explain what 'can be opened' means operationally (e.g., HTTP response, DNS resolution, port reachability) or what side effects or return values to expect. The schema hints at unrelated behaviors like normalizing, citing, and discarding other inputs, which are not addressed in the 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 two short sentences with no filler, and both sentences convey useful information: the core action and a key behavioral caveat. It is appropriately concise for the limited scope stated, though it lacks some depth that might be expected given the schema's complexity.

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 a rich schema with seven heterogeneous parameters, yet the description covers only the URL aspect and does not mention what the other parameters are for or that they are discarded. There is no output schema, and the description does not explain return values, error semantics, or how to interpret 'can be opened.' This leaves the tool incompletely specified for an agent.

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 descriptive text for all seven parameters, so schema coverage is high and the baseline is 3. The description adds no parameter-level guidance and does not clarify why parameters such as ref, city, feed, or json are present or how they relate to the stated URL-checking purpose. An agent cannot tell which parameter is the primary one, though 'url' is obvious from context.

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.' This is clear and implies a lightweight validation task. The added clause 'No browser is launched' hints at a difference from browser-launching sibling tools, but no sibling is named, so differentiation is only implicit.

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 implies a usage context: use this when you need to know if a URL is openable without launching a browser. However, it does not explicitly say when to prefer this tool over alternatives such as playwright-url-ok or fetch-status, nor does it mention any exclusions or prerequisites.

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