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

No annotations are provided, so the description carries the full burden. It discloses the HEAD method and that only status is returned, which is useful, but it says nothing about the other parameters' behaviors (e.g., discarding values after shape checks) or about authentication, rate limits, or what happens when multiple parameters are supplied. The schema mentions 'discarded after the shape check' for several params, but this 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 with no wasted words, which is concise. However, it is under-specified for a tool with nine parameters and no annotations, so while the structure is fine, the brevity comes at the cost of essential information.

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?

For a tool with nine optional parameters, no output schema, and no annotations, the description is grossly incomplete. It omits the multi-purpose nature implied by the schema, does not clarify return values or error handling, and provides no context on how the parameters are used. An agent would not know which parameter to pass for the described behavior or whether other parameters trigger different checks.

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 each parameter has a description, but the tool description adds no guidance on which parameter is the URL for the HEAD request. The schema describes 'url' as 'HTTPS URL to normalize or cite', which conflicts with the description's implication that a URL is checked for status. The relationship between the described action and the parameters is unclear, and the description does not compensate for this ambiguity.

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 action ('HEAD a public URL and return status only'), which is clear for that single case. However, it fails to convey that the tool accepts nine other parameters (ref, city, feed, host, json, path, zone, query) with purposes like validating JSON or checking timezones, making the overall purpose ambiguous and indistinguishable from siblings like browser-url-ok or web-fetch.

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 siblings such as web-fetch, browser-url-ok, or validate-json. The description only implies a use case for URL status checks but does not mention exclusions or alternatives.

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