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 the body is discarded, but it does not mention that the tool makes a network request, how it handles unreachable URLs, what status codes are returned, or any rate limiting or error behavior.

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, well-structured sentence that immediately conveys the core behavior and a key limitation. It is concise and front-loaded, though it omits some important operational details.

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, no output schema, and no annotations, the description is too sparse. It does not explain the relevance of the many non-URL parameters, nor does it describe the response format, error cases, or network behavior, leaving significant gaps for an agent trying to use it correctly.

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?

Although every parameter has a description, the tool description only explains the url param's purpose ('public URL'). Several params (ref, city, feed, json, path, zone, query) are not tied to the stated purpose of fetching HTTP status/content type, and phrases like 'discarded after the shape check' are unexplained, creating confusion rather than clarity.

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 and resource: it returns HTTP status and content type for a public URL, and explicitly notes the body is discarded. This is clear, though it does not explicitly distinguish itself from similar sibling tools like fetch-status.

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 gives a minimal usage hint ('for a public URL') and clarifies that the body is not returned, but it does not state when to prefer this tool over siblings such as fetch-status, normalize-url, or browser-url-ok, nor does it explain what the tool does not do beyond discarding the body.

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