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

With no annotations, the description must disclose side effects. It adds one useful negative fact ('No browser is launched') but does not disclose whether the tool makes a network request, how it determines 'can be opened,' or what errors/limitations apply.

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 and front-loaded with the main action, followed by a relevant behavioral clarification. No fluff or redundant wording is present.

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 ambiguous optional parameters and lack of an output schema, the description leaves important context unexplained: what result is returned, what an 'OK' result means, and how the parameters relate to the check. It is not complete enough for an agent to use confidently.

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 description provides no parameter semantics, and the schema's nine optional parameters are confusingly unrelated to the stated purpose. Several descriptions ('Git ref name; discarded after the shape check,' 'City name for a public weather hint') do not clarify how to invoke the URL check.

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 names a recognizable action and target: 'Check whether a URL can be opened.' However, 'opened' is vague and no mechanism is given, so it does not strongly distinguish from sibling tools like browser-url-ok, fetch-status, 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 given for when to choose this tool over related tools. The only usage hint is the negative behavior 'No browser is launched,' which implies a lightweight check but does not state when it should be preferred.

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