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

With no annotations, the description must carry the behavioral burden. It discloses that it performs a HEAD request (read-only) and returns only status, but it does not explain what happens with the other parameters, whether it follows redirects, handles timeouts, or has side effects. The schema descriptions mention parameters being 'discarded,' but that information is not in the tool description, so an agent cannot infer the full behavior.

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 with no wasted words. It efficiently states the core action and output. However, it is arguably too terse given the tool's complexity, as it omits the broader purpose. Still, for what it conveys, it is concise and well-structured.

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 9 parameters, no output schema, and no annotations, yet the description explains only one use case (URL status). It does not cover the other 8 parameters, the return format beyond 'status only,' or any edge cases. An agent cannot determine how to use this tool correctly for non-URL inputs or what statuses are returned. This is severely incomplete for a tool of this complexity.

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. The description does not add any meaning beyond the schema; it only mentions 'URL' and 'status' without detailing any parameter. Since the schema already documents each parameter thoroughly, the description's lack of parameter info is acceptable, but it also does not synthesize or clarify the relationships among parameters.

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 ('HEAD a public URL') and output ('status only'), which is clear for the URL case. However, the input schema contains 8 other parameters (ref, city, feed, host, json, path, zone, query) that are not URLs, so the description does not reflect the tool's full scope. It does not distinguish from siblings like browser-url-ok or web-fetch beyond the HEAD method.

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. It does not mention when to prefer it over browser-url-ok, normalize-url, or web-fetch, nor does it state any exclusions or prerequisites. The only implicit signal is the HEAD method, but no explicit comparison is provided.

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