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, but it only reveals that no browser is launched. It does not clarify whether the tool performs a network request, validates URL syntax only, or what 'can be opened' actually means, leaving 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 two short sentences and front-loads the core action before the behavioral qualifier. It is efficient and free of fluff, though the brevity sacrifices important 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?

For a tool with nine optional parameters, no annotations, and no output schema, a short description is not enough to tell an agent which parameter to supply or what result to expect. The return value, actual check semantics, and parameter-selection logic are all unspecified.

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?

Schema description coverage is 100%, so each parameter already has a meaningful description, including notes that values are 'discarded after the check.' The tool description adds no parameter-level meaning and does not indicate that 'url' is the primary parameter among the nine, so it neither improves nor harms parameter semantics.

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 specific action ('Check whether a URL can be opened') and a resource ('URL'), and 'No browser is launched' helps distinguish it from the sibling browser-url-ok. However, it focuses only on URL checking while the schema exposes nine unrelated parameters, so the purpose is not fully aligned with the tool's actual surface.

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 phrase 'No browser is launched' implies a use case where browser automation should be avoided, which is a useful contrast with browser-url-ok. But it never explicitly names alternatives or states when to choose this over fetch-status, web-fetch, or normalize-url, so the usage guidance is implicit rather than explicit.

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