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

With no annotations, the description carries the full burden. It discloses that it performs a HEAD request (a read-only operation) and returns only the status, which is a useful behavioral trait. However, it does not explain how it handles the various non-URL parameters, whether it makes network calls in all cases, or any side effects. The description provides some transparency but lacks depth for a tool with such a broad input schema.

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 that front-loads the core action and output. It is concise and avoids fluff. However, it is so brief that it omits important context about the tool's broad input scope, which could mislead an agent. The conciseness is appropriate for a simple tool, but a bit more detail would make it more useful without sacrificing brevity.

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 covering a wide range of unrelated inputs (URLs, city names, JSON text, timezone names, etc.) and no output schema. The description only addresses URL handling, leaving the behavior for all other input types unexplained. An agent would have no idea why a 'city' parameter exists or how it affects the status check, making the description incomplete for the tool's real 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 coverage is 100%, and each parameter has a description in the schema itself. The tool description adds no additional meaning about the parameters. For example, it does not clarify how 'city' or 'zone' feed into the status check, nor does it explain the 'discarded after' semantics beyond what the parameter descriptions already state. Since the schema already documents each parameter thoroughly, the description does not need to repeat them, but it also does not enhance understanding.

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 clear verb and resource: 'HEAD a public URL and return status only.' This is a specific, distinctive operation that differentiates it from siblings like web-fetch (which fetches content) and normalize-url (which normalizes URLs). However, it is narrow and does not reflect the full input schema, which accepts many non-URL fields like city, json, and zone, making the stated purpose incomplete relative to the tool's actual capabilities.

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?

There is no guidance on when to use this tool versus its alternatives. The description does not mention any sibling tools, prerequisites, or exclusion conditions. The only implicit signal is the purpose itself, which suggests use when you need the HTTP status of a URL, but it fails to contrast with similar tools like browser-url-ok or web-fetch, leaving the agent to guess which to choose.

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