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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose that no browser is launched, which is a useful trait, but it fails to explain what the check actually does (e.g., does it make an HTTP request, only validate syntax?) or what side effects might occur. The presence of nine unrelated parameters (ref, city, json, path, zone, etc.) is unexplained and suggests the tool has a broader scope than the description implies, creating confusion about its actual behavior.

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 concise (two short sentences) and front-loaded with the purpose. However, given the tool's complexity (nine parameters, no annotations, no output schema), the description is too sparse to be considered well-structured. It omits critical information about what the check entails and how parameters are used, making it under-specified rather than efficiently concise.

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 description is far from complete for a tool with nine parameters and no annotations. It doesn't explain the return value (no output schema), doesn't clarify the purpose of the many parameters, and doesn't describe the exact nature of the URL check. An agent would struggle to know when to use this tool and what it actually does beyond a vague 'can be opened' check.

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 schema covers all parameters with descriptions (100% coverage), so the baseline is 3. The tool description itself does not add any parameter-level meaning beyond what the schema already provides. It doesn't clarify how these parameters relate to the URL check or why they are accepted, but since the schema documents each one, the description's lack of additional info is not a significant failure.

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 clear verb and resource: 'Check whether a URL can be opened.' It also distinguishes itself by explicitly saying 'No browser is launched,' which sets it apart from tools like playwright-url-ok. However, it doesn't specify what 'can be opened' means (e.g., network reachability vs. format validation), and it doesn't name sibling alternatives, leaving some ambiguity.

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 offers no guidance on when to use this tool versus alternatives. Sibling tools like fetch-status, normalize-url, and web-fetch exist, but there is no mention of them or any conditions that would favor one over the other. The only hint is the 'No browser is launched' note, which implies it's a lightweight check, but this is not elaborated.

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