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

No annotations exist, so the description carries the full burden. It discloses one behavioral trait: 'Page content is not stored,' which is useful privacy context. However, it does not state whether the tool performs a network request, how it handles invalid URLs, whether redirects are followed, or what error responses look like. The disclosure is partial.

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 primary action and includes a privacy note. Every word is necessary; no filler or redundancy. It is as concise as possible while conveying the core purpose.

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 9 optional parameters, no output schema, and no annotations, the description is far too brief. It does not explain how the parameters relate (e.g., precedence, mutual exclusivity), what the return format is (JSON? fields?), or why unrelated parameters like 'city' or 'ref' exist. An agent cannot confidently construct a correct call beyond guessing the 'url' parameter.

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 baseline is 3. The description says 'for a URL' but does not specify which of the 9 optional parameters is the primary URL input. It adds no meaning beyond the schema for any parameter. While the schema itself has descriptions, the tool description fails to guide which parameter to use, making the semantics ambiguous for an agent.

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?

States a specific verb and resource: 'Return host, scheme, and HTTP status for a URL.' This is unambiguous and distinguishes it from siblings like normalize-url (which likely only normalizes) or fetch-status (which may return full page status). The addition of 'Page content is not stored' reinforces the scope.

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?

No guidance on when to use this tool versus alternatives. There are many related siblings (fetch-status, normalize-url, browser-url-ok), but the description does not mention any of them or provide conditions for choosing this tool. An agent cannot infer when to prefer 'citation' over a sibling.

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