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

With no annotations, the description must disclose behavior fully. It only states that no browser is launched, but does not explain what the check actually does (e.g., network request, format validation) or why parameters like city, json, path, zone, and query are present. These extra parameters are unexplained and contradict the single-purpose framing, leaving significant behavioral ambiguity.

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 very concise at two sentences, with no wasted words. However, it is under-specified, leaving essential details unaddressed. It is not bloated, but it is too short to be genuinely helpful, so it earns a mid-range score.

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?

For a tool with 9 parameters, no annotations, and no output schema, the description is grossly inadequate. It does not explain what the output is, what 'can be opened' means, how the parameters affect the check, or when to use it. The presence of unrelated parameters like city and json makes the tool's behavior even more opaque. This is far below the minimum viable completeness for such a complex tool.

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%, so the baseline is 3. However, the parameter descriptions are cryptic and disconnected from the tool's stated purpose (e.g., 'City name for a public weather hint; discarded after the call'), and the description adds no additional meaning. The tool description does not clarify why these parameters exist or how they relate to checking URL openability, so it fails to compensate for the schema's lack of contextual integration.

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 specific action ('Check whether a URL can be opened') and resource ('URL'), and differentiates itself from siblings like web-fetch or playwright-url-ok by noting 'No browser is launched.' However, it leaves ambiguity about what 'can be opened' means (e.g., HTTP status, DNS resolution, URL format), so it is clear but not fully precise.

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 guidance is given on when to use this tool versus alternatives. It does not mention any conditions, prerequisites, or why one would choose it over web-fetch, normalize-url, or playwright-url-ok. The only hint is that no browser is launched, but this is not framed as a use-case directive.

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