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

Since no annotations are provided, the description carries the full burden of behavioral disclosure. It only mentions the URL case, but the schema includes eight other parameters (e.g., ref, city, json, zone) that are implied to be checked and discarded; the description does not surface this broader behavior. This makes the tool's actual operations unclear and potentially misleading, as an agent might assume it only accepts a URL.

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, front-loaded sentence that conveys the core action efficiently. It is concise and easily parsed, with no extraneous words. However, its brevity comes at the cost of omitting necessary context about the full input surface, which slightly offsets the structural quality.

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 nine optional parameters, no output schema, and is surrounded by many distinct siblings (web-fetch, normalize-url, browser-url-ok, etc.). The description is far too minimal to cover this complexity—it does not explain the purpose of non-URL parameters, the return format, or when to select it over alternatives. An agent cannot reliably determine how to invoke it correctly for anything beyond a simple URL check.

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 100% coverage with a description for each of the nine parameters, so the baseline is 3. The tool description adds no additional semantics beyond what the schema already states; it merely highlights the URL as central but does not clarify the role of other parameters. It neither elevates nor degrades the schema-provided information.

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 ('HEAD a public URL') and the output ('status only'), which is unambiguous about the primary use. However, it does not differentiate from siblings like web-fetch or normalize-url, leaving some ambiguity about when this tool is preferred. The core purpose is clear for the URL case, though the schema implies a broader scope.

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 web-fetch or playback-url-ok. There is no mention of scenarios where a HEAD request is advantageous, nor any exclusions or prerequisites. An agent would have to infer usage entirely from the name and the brief description, which is insufficient given the many siblings.

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