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

With no annotations present, the description carries the full burden of explaining side effects and behavior, but it only says 'No browser is launched.' It does not state whether the tool makes a network request, what it returns, whether it has side effects, or what error conditions may arise.

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: one sentence and no filler. Every word contributes to the core purpose or to an important limitation.

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?

The tool has nine optional parameters, no output schema, and no annotations, yet the description only gives a one-line purpose. It does not explain parameter usage, return value, error behavior, or how it relates to sibling tools, leaving the agent with insufficient context to call it 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 does not mention any parameters, and the input schema is largely unrelated to the stated purpose—fields like city, json, path, and zone appear alongside url with generic 'discarded after the shape check' notes. There is no guidance on which of the nine optional parameters should be supplied or how they relate to checking a URL.

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 that the tool checks whether a URL can be opened and explicitly notes that no browser is launched, giving a concrete action and resource. It is slightly vague about what 'can be opened' means—valid URL, reachable endpoint, or something else—but the primary purpose is understandable.

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 provides almost no guidance on when to use this tool versus alternatives like fetch-status, normalize-url, or playwright-url-ok. The phrase 'No browser is launched' hints that it is not for browser-rendering checks, but it does not explicitly name sibling tools or explain when this tool should be preferred.

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