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

With no annotations, the description must fully disclose behavior. It reveals that no browser is launched, but fails to state whether a network request occurs, whether the operation is read-only, or what side effects might exist. The mechanism of the check and any return behavior are also unexplained.

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 sentences with no redundancy. The core action and the key differentiator (no browser) are front-loaded, making it efficient. It is appropriately sized for the tool's apparent simplicity, though it could benefit from a bit more 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 9 optional parameters, no output schema, and many similar siblings, the description is incomplete. It doesn't explain what 'can be opened' means, what the tool returns, or how to decide between this and related tools like browser-url-ok or fetch-status. An agent would lack sufficient context to invoke it correctly.

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 coverage is 100%, so every parameter already has a description. The tool description adds no parameter-level information, so it provides no extra semantics beyond what the schema already defines. Baseline 3 is appropriate for high schema coverage.

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 clearly states the action: 'Check whether a URL can be opened.' It also explicitly differentiates from siblings by noting 'No browser is launched,' which distinguishes it from browser-url-ok. The verb-resource pairing is specific and unambiguous.

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 implies a lightweight check without a browser but does not explicitly state when to use this tool versus alternatives like browser-url-ok or fetch-status. No exclusions or conditions are provided, leaving the agent to infer usage context from the 'no browser' hint.

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