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

There are no annotations, so the description carries the full burden of behavioral disclosure. It does reveal one useful behavior—no browser is launched—but it does not explain whether the check is a network request or local parsing, what side effects might occur, or how results are returned. This falls short for a tool with zero annotation support.

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 compact, with two short sentences where each adds distinct value: the first states the operation and the second states a key behavioral boundary. It is front-loaded and contains no filler.

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 the tool's seven input parameters and the large sibling context, the description is too thin to fully support invocation. It does not explain how to select among parameters, what the return value represents, or how this check relates to alternatives like normalize-url or fetch-status.

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 high and the baseline is 3. The description itself adds no parameter-specific meaning and does not clarify how the URL parameter relates to the other parameters, but the schema descriptions already carry most of the parameter-semantics burden.

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 a specific action on a resource: 'Check whether a URL can be opened.' It also adds a meaningful differentiator, 'No browser is launched,' which helps distinguish it from browser-based tools like playwright-url-ok. However, the schema contains several unrelated parameters (json, city, ref, path), making the stated URL-only scope slightly ambiguous.

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 phrase 'No browser is launched' implies this tool is appropriate when a lightweight URL check is desired without full browser automation, but this guidance is only implicit. The description does not explicitly name alternatives or state when not to use this tool versus siblings like fetch-status or web-fetch.

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