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 helpfully reveals that no browser is launched, which is a meaningful behavioral trait and prevents the agent from assuming a heavy browser context. However, it does not disclose whether a network request is actually made, whether the operation is read-only, or what side effects or response behavior to expect, so the behavioral picture remains incomplete.

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, with two short sentences that communicate the essential purpose and the key behavioral caveat. It is front-loaded and avoids unnecessary words. The only reason it does not score 5 is that the terse phrasing leaves out context that would likely be needed for correct tool selection and invocation, such as what the tool returns or which parameter to prioritize.

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 seven input parameters, no annotations, and no output schema, yet the description only states a vague check on a URL and the lack of a browser launch. It does not explain expected return values, potential network effects, error conditions, or which parameters are relevant to the primary check. For a tool with this parameter complexity, the description is not complete enough for an agent to confidently invoke and interpret results.

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 input schema provides descriptions for all seven parameters, so schema coverage is effectively 100%, setting a baseline of 3. The description itself does not add parameter-level meaning, nor does it clarify the relationship between the stated 'URL' focus and parameters like ref, city, feed, host, json, and path. This is acceptable because the schema already documents each parameter, but the description adds no extra semantic value.

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, which conveys the core purpose and resource. It also distinguishes itself from siblings like browser-url-ok by noting that no browser is launched. However, it does not explicitly define what 'can be opened' means or fully differentiate from fetch-status or web-fetch, so it stops slightly short of 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 description gives no guidance on when to use this tool versus alternatives such as browser-url-ok, fetch-status, or web-fetch. It states 'No browser is launched,' which hints at a lightweight use case, but it does not explicitly say when this tool is preferred or when another sibling should be used. This leaves the agent to infer usage context.

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