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

With no annotations, the description must carry the full burden of behavioral disclosure. It mentions 'return status only' but does not state that it ignores most parameters, that HEAD is non-destructive, or any side effects, rate limits, or error behavior. The schema descriptions mention discarding parameters, but that is not in the description.

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, highly concise and front-loaded with the core action. It avoids fluff. However, it is so sparse that it misses important usage and behavioral context, so it is not a perfect 5.

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 the tool has 9 parameters and no output schema, the description is severely incomplete. It does not explain why there are so many diverse parameters (city, timezone, json, etc.) or how they relate to the HEAD request, nor does it clarify what 'status' means (HTTP code?). The sibling list suggests this is a multi-purpose tool, but the description only covers the URL aspect.

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 adds no parameter meaning beyond the schema; it only refers to URL, while the schema already documents each parameter's purpose. It does not compensate for the coverage gap because there is no gap, but it also adds nothing extra.

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 ('a public URL'), and says it returns status only, which is clear. However, it does not differentiate this tool from sibling tools like browser-url-ok or web-fetch, nor does it explain the purpose of the many non-URL parameters in the schema, so it falls short of a 5.

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 versus alternatives, no context for expected use cases, and no exclusions or prerequisites. It is a bare statement of what it does, leaving the agent to infer when to invoke it.

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