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

With no annotations, the description carries the full burden. It discloses only that no browser is launched, but does not mention network behavior, side effects, return values, or error cases.

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 short and front-loads the core action plus a key behavioral caveat. It is concise, though it omits necessary context.

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?

Given 9 parameters, no output schema, and no annotations, the description is far from complete. It fails to explain return format, which parameters are relevant, how to interpret a negative result, or how this differs concretely from browser-url-ok.

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?

Although the schema covers all 9 parameters, the descriptions conflict with the tool's stated purpose. The url parameter is described as 'normalize or cite' rather than 'open/check,' and the other parameters (ref, city, feed, json, etc.) appear unrelated to URL checking, leaving the agent confused about which inputs are actually used.

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 clearly states the tool checks whether a URL can be opened and adds a distinguishing note that no browser is launched. However, it does not explicitly identify which input parameter carries the URL, and the schema's url description suggests a different purpose.

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 gives no explicit guidance on when to prefer this tool over siblings like browser-url-ok or fetch-status. The 'No browser is launched' note only weakly implies a non-browser check and does not state conditions or alternatives.

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