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

With no annotations, the description carries the transparency burden. It does disclose a key behavior—no browser is launched—and implies a read-only reachability check. But it does not say whether a network request is made, what side effects may occur, what the tool returns, or how the check is performed.

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 concise, purposeful sentences: the first states the core purpose and the second provides a critical behavioral qualifier. There is no filler, repetition, or unnecessary detail.

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 required fields, no output schema, and no annotations, yet the description does not specify required inputs, result format, or how to invoke it correctly. The short description is insufficient for an agent to make confident call decisions.

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 descriptions cover 100% of parameters, so the baseline is 3, and the tool description adds no additional parameter-level meaning. It also does not clarify which of the nine optional fields is the actual URL to check, leaving room for confusion despite 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 tool checks whether a URL can be opened, with the important qualifier that no browser is launched. This gives a specific action and resource and partially separates it from browser-based sibling tools, though 'opened' is left somewhat underspecified.

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 browser is launched' implies this is a lightweight, non-rendering check and can guide an agent toward it when a browser is not needed. However, it does not explicitly name alternatives like browser-url-ok, fetch-status, or web-fetch, nor state when to prefer those instead.

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