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

Without annotations, the description carries the behavioral burden. It adds a useful privacy-relevant behavior ('Page content is not stored') and implies an HTTP status check, but it does not disclose whether a network request is made, redirect/error behavior, or any rate limits.

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?

Two short sentences, with the most important information front-loaded and no wasted words. The non-storage note earns its place as a behavioral clarification.

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 simple URL metadata tool, the key output fields are stated and the safety-relevant non-storage behavior is included. However, with no output schema or annotations and several overlapping siblings, the description could be more complete about return shape and when to pick this tool over fetch-status, normalize-url, or web-fetch.

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?

The input schema already has 100% property descriptions, so the baseline is 3. The description reinforces that a URL is the relevant input but does not clarify how the many optional parameters (ref, city, feed, host, json, path) relate to the tool; the schema covers them individually.

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 uses a specific verb ('Return') with a clear resource and output set: host, scheme, and HTTP status for a URL. It is unambiguous, but it does not explicitly distinguish itself from similar siblings such as normalize-url or 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 phrase 'for a URL' gives implied context that this tool is for URL metadata lookup, and 'Page content is not stored' hints it is not for content retrieval. However, it provides no explicit when-to-use, when-not-to-use, or alternative tool guidance.

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