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

As no annotations are provided, the description carries the full burden. It clearly discloses that this is a HEAD request (non-destructive, no body) and that it works only on public URLs. However, it is silent about the tool's many other parameters (city, feed, json, path, zone, query) and how they interrelate, leaving the behavioral model incomplete for these inputs.

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 one tight sentence that is front-loaded with the action (HEAD) and the outcome (status only). Every word earns its place; there is no filler. It effectively communicates the essential purpose in the fewest words.

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?

With 9 parameters and no output schema, the description is far too minimal to be contextually complete. It only explains the `url` usage, leaving all other parameters unexplained in the overall behavior. Even though the schema has 100% coverage, the description's silence on how these parameters are used (or ignored) would confuse an agent trying to invoke the tool for a non-URL input. A more complete description would clarify the multi-purpose nature of the 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 coverage is 100%, so the baseline is 3 even without extra parameter information. The description adds no meaning beyond the schema itself; it only says 'HEAD a public URL', which indirectly matches the 'url' parameter but does not explain the relevance of the 8 other parameters. Given the schema is thoroughly documented, the description simply doesn't augment it.

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 the verb (HEAD), the resource (public URL), and the expected output (status only), making the tool's purpose immediately clear. It distinguishes this tool from content-fetching siblings like web-fetch and browser-url-ok, which would retrieve more than status. The phrase 'status only' sets precise expectations.

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 implies usage: use it when only the status of a public URL is needed, but it never explicitly names alternative tools or conditions for choosing this one. With siblings like browser-url-ok and playwright-url-ok, the lack of an explicit 'use this instead when X' leaves some inference to the agent. It gets a 3 because the purpose strongly implies the situation, but no direct guidance is provided.

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