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

Annotations are absent, so the description carries the full burden. It says 'HEAD a public URL and return status only,' but does not disclose that most of the 9 parameters (ref, city, feed, json, path, zone, query) are discarded and only URL is actually used. It also doesn't mention authentication, rate limits, or response format beyond 'status.' The behavior is only partially transparent.

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 a single sentence with no filler, and the verb and core action are front-loaded. It is appropriately concise for a simple tool, though it could arguably be expanded to clarify parameter usage. The structure is efficient and clear.

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 9 parameters, no output schema, and no annotations, the description is notably incomplete. It doesn't explain what 'status' means (HTTP status code?), how the many parameters are handled, or whether the tool has any side effects. The schema descriptions help individually, but the tool description fails to tie them together or clarify the actual input scope. An agent would struggle to know that only URL matters.

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 parameter has a clear description (e.g., 'discarded after the shape check'). The tool description adds no extra semantic value beyond the schema; it only repeats the idea of a URL. With high schema coverage, a baseline of 3 is appropriate since the schema does the heavy lifting.

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 verb ('HEAD') and resource ('public URL'), and explicitly says it returns only status. This clearly differentiates from sibling tools like web-fetch, browser-url-ok, and playwright-url-ok, which imply fetching content or full checks. The purpose is unambiguous.

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 provides no guidance on when to use this tool over the many alternatives. With siblings like web-fetch, browser-url-ok, and playwright-url-ok, there is no statement of conditions or exclusions. An agent must infer from the name and one-liner that it's for status-only checks, which is not explicit.

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