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

With no annotations, the description must disclose behavioral traits. It mentions 'No browser is launched,' which is a useful note, but it fails to disclose that all parameters are discarded after their respective checks, that the tool performs shape or length validations, or what it actually returns. The single behavioral note is insufficient for a tool with such a broad parameter set.

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 extremely concise (two sentences) and the key statement is front-loaded, which is positive. However, it is too terse to be useful for a tool with nine parameters and multiple sibling tools; the brevity sacrifices necessary context, making it feel under-specified rather than efficiently structured.

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 complexity (9 optional parameters, no output schema, no annotations) and the rich set of sibling tools, the description is severely incomplete. It does not explain the tool's multi-purpose validation behavior, what constitutes a successful check, or how the URL check relates to the other parameters. An agent cannot call this tool correctly based on the description alone.

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 100% coverage with each parameter having a description (e.g., 'discarded after the shape check'), so the schema already explains the individual parameters. The tool description adds no extra meaning about how the parameters relate or which one is central, so it neither compensates for nor exceeds the schema's baseline.

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 'Check whether a URL can be opened' with a specific verb and resource, but the input schema includes nine diverse parameters (city, timezone, JSON, file path, etc.) that clearly indicate a much broader validation purpose. This mismatch makes the stated purpose misleading and vague, as it does not reflect the actual scope of the tool.

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 about when to use this tool versus its many siblings (e.g., browser-url-ok, fetch-status, normalize-url). The description offers no context, exclusions, or alternatives, leaving the agent without any routing information.

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