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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose the important trait that no browser is launched, but it omits other behavioral details such as whether a network request is made, what the return value indicates, or how invalid URLs are handled. This is too sparse for a tool with no 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 two short sentences with the core purpose first and the clarifying caveat second. There is no fluff or repetition. It is appropriately sized for a simple tool, though additional behavioral context would be welcome in a longer but still structured form.

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?

Despite having 9 parameters and no output schema, the description does not explain what 'ok' means, what the tool returns, or how the URL is checked. The schema clarifies parameter meanings, but the overall invocation semantics remain under-specified. An agent could not confidently predict the tool's behavior beyond 'no browser is launched.'

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%, and each of the 9 parameters has its own description in the schema, including notes about being discarded. The tool-level description adds no parameter-specific meaning, but it does not need to because the schema already documents each parameter. This meets the baseline for 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 states a clear verb and resource: 'Check whether a URL can be opened.' The phrase 'No browser is launched' helps distinguish it from sibling tools like playwright-url-ok. However, 'can be opened' is slightly ambiguous—it does not specify whether this is a syntax check, a network check, or some other validation.

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 implies this tool is for lightweight URL checking without launching a browser, which is useful context against playwright-url-ok. However, it does not explicitly state when to prefer this tool over alternatives like normalize-url, fetch-status, or web-fetch. No exclusions or alternative selection criteria are provided.

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