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

With no annotations provided, the description carries the burden of behavioral disclosure. It does disclose one meaningful behavior: no browser is launched. Yet it omits other important behaviors such as whether a network request is made, what the return value is, or whether there are side effects.

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 with no filler, and the core action is front-loaded. It is appropriately succinct, though it may be too terse to fully support the missing behavioral and usage 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?

Given nine optional parameters, no output schema, no annotations, and numerous sibling tools, the one-line description is incomplete. It does not explain return behavior, when to use this over alternatives, or how the non-URL parameters fit. The schema fills some gaps, but the tool-level context remains under-specified.

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 the schema already documents all nine parameters clearly. The description adds no additional parameter semantics and even emphasizes only 'url' while the schema supports a broader set of inputs. This matches the baseline of 3 for fully schema-covered parameters.

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 identifies a specific action—'Check whether a URL can be opened'—and adds a distinguishing caveat, 'No browser is launched.' This differentiates it from browser-launching siblings like browser-url-ok. However, 'opened' is somewhat ambiguous: it could mean HTTP reachability, URL syntax, or something else, which prevents a 5.

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 'No browser is launched' phrase implies a lightweight, non-browser context, giving some usage signal. But no explicit when-to-use or when-not-to-use guidance is provided, and no alternative tools are named. The agent is left to infer when this is preferable to browser-url-ok or fetch-status.

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