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

There are no annotations, so the description carries the full burden of behavioral disclosure. It states that a HEAD request is made and only the status is returned, which is clear. However, it omits that the tool accepts many other parameters and discards them after validation, which could surprise the agent. It also does not mention that the operation is read-only (though HEAD implies this) or any potential rate limits or side effects.

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, concise sentence that is front-loaded with the main action. It is efficient and easy to parse. However, it is so sparse that it fails to convey the tool's broader scope, which is a completeness issue rather than a conciseness problem. The brevity itself is appropriate.

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 optional parameters, no output schema, and 26 sibling tools. The description only covers the URL use case and gives no indication that the tool handles many other input types, nor does it explain the status semantics or provide any usage context. This is severely incomplete for an agent to use the tool correctly across its full parameter set.

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% and each parameter has a descriptive explanation (e.g., 'discarded after the shape check'). The tool description adds no parameter information, but since the schema already covers all parameters, the baseline of 3 applies. The description does not conflict with the schema.

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 (public URL) with a clear outcome (return status only). However, the input schema contains 9 parameters covering many different resources (city, feed, JSON, timezone, etc.), which the description does not mention at all. This narrows the tool's apparent purpose to a single use case and does not differentiate it from sibling tools like browser-url-ok or normalize-url, which also handle URLs.

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 the many sibling tools. It does not mention alternatives, exclusions, or any context for selection. With 26 sibling tools listed, the absence of any routing information is a critical gap.

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