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

With no annotations, the description carries the burden and does state useful behavioral facts: it uses HEAD, targets public URLs only, and avoids returning body content. Missing are redirect behavior, timeouts, error semantics, and the fact that several input values are explicitly discarded, which the schema hints at but the description does not.

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 efficient sentence with no filler and front-loads the key action. It is concise, though it is arguably too terse given the tool's 9-parameter schema and lack of an output schema.

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 description is incomplete for the tool as defined: it only covers the URL HEAD case while the schema shows 8 other potential input kinds, and there is no output schema or annotations to fill in behavior. An agent would not know how to use this tool for feed, host, json, path, zone, query, ref, or city inputs, nor what the returned 'status' looks like.

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 schema already explains each parameter in some detail, including discard behavior. The tool description adds no parameter-level meaning and does not connect 'HEAD a public URL' to the 'url' parameter, leaving some ambiguity about how the other eight parameters relate to the stated purpose.

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 names a specific verb (HEAD), resource (public URL), and result (status only), so the core action is clear. It also implicitly distinguishes itself from content-fetching siblings like web-fetch and browser-url-ok. However, the input schema exposes 9 unrelated optional parameters (ref, city, feed, json, zone, etc.), which the description never acknowledges, so the full purpose is not conveyed.

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 phrase 'return status only' implies a use case: use this when you need a lightweight status check and not page content. But the description gives no explicit guidance about when to prefer this over similar sibling tools, no exclusions, and no mention of what to do when the input is not a URL.

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