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

The description explicitly states that no browser is launched, which is a useful behavioral detail. However, it does not disclose side effects, required permissions, error behavior, or what happens with the many non-URL parameters (e.g., are they ignored or validated?). With no annotations, this partial disclosure leaves significant behavioral ambiguity.

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—a single sentence with no redundant wording. This is efficient, but it sacrifices necessary detail. The structure is simple and easy to parse, though it lacks any breakdown of inputs or behavioral notes beyond the one sentence.

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 has 9 parameters, no output schema, and no annotations, the description is far from complete. It omits critical context: what the return value indicates, how to interpret failures, which parameters are actually used for the URL check, and when this tool is preferable to alternatives. The absence of this context makes it inadequate for an agent to use reliably.

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 provides descriptions for all 9 parameters, but the tool description adds no additional meaning about how they relate to the URL check. Several parameters are marked as 'discarded after the shape check' or similar, suggesting they are auxiliary, yet the description does not explain their purpose or why they exist. The parameter descriptions themselves are vague and disconnected from the tool's stated function.

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 purpose: checking whether a URL can be opened, and explicitly notes that no browser is launched, which helps differentiate it from browser-based sibling tools. However, it does not mention the array of unrelated parameters in the schema, so the scope is only partially clarified.

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 guidance on when to use this tool versus alternatives like browser-url-ok or fetch-status. It fails to explain what inputs are relevant, how to call it, or what constitutes a successful check, leaving an agent to infer usage from the name and schema alone.

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