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

With no annotations, the description carries the full burden of behavioral disclosure. It does reveal that no browser is launched, but it does not explain what actually happens for each of the nine accepted parameters, whether network requests occur, what side effects exist, or what the response format is. For a tool with such heterogeneous inputs, this is insufficient.

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 (one sentence) but not appropriately sized for the tool's complexity. It front-loads a narrow purpose while omitting the multi-parameter nature, making it under-specified rather than efficiently concise. A tool with nine parameters and many siblings requires more structure and detail.

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 the tool's high complexity (9 parameters, no required fields, no output schema, and many sibling tools), the description is grossly incomplete. It fails to explain the tool's actual scope, how to choose among parameters, what results are returned, or any constraints. An agent cannot reliably invoke this tool correctly based on the current description.

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 (100%), so the baseline is 3, but the tool description adds zero semantic value for parameters. It does not explain that parameters are likely mutually exclusive, which one to use for a given task, or how they map to the described 'URL check'. The description's narrow focus on URLs contradicts the parameter set, leaving agents to infer parameter usage from cryptic schema descriptions alone.

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'), but the input schema exposes nine unrelated parameters (ref, city, feed, json, path, zone, query, etc.), implying the tool is a multi-purpose validator. The description fails to capture this broader scope, making it misleading about the actual functionality and not distinguishing it from siblings like browser-url-ok or normalize-url.

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?

No guidance is provided on when to use this tool versus any of the 28 sibling tools. There is no mention of alternatives, exclusions, or conditions that would route an agent to this specific tool. The description is a single generic sentence that offers no decision-making support.

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