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

With no annotations, the description carries the full burden and discloses one meaningful behavior: 'Page content is not stored.' It does not state whether the URL is fetched over the network, how redirects or errors are handled, or any authentication/rate-limit considerations, so the safety profile remains thin.

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 core operation front-loaded and a valuable disclaimer in second place. No filler or redundant restatement.

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 description is incomplete relative to the schema: json ('JSON text to validate') and zone ('IANA timezone name') are unexplained by the tool description and the prose describes outputs (host, scheme, status) that only loosely map to the schema properties. With no output schema and no annotations, an agent cannot confidently predict behavior for the non-URL inputs.

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 description coverage is 100% (the 'url', 'host', 'json', and 'zone' properties all have descriptive text), so the baseline is 3. The tool description itself adds no parameter information and does not explain how the optional fields relate to the described URL behavior.

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 names a concrete action and output ('Return host, scheme, and HTTP status for a URL') and adds a scope-limiting side-effect note. It does not, however, reconcile this URL-only purpose with the schema's unrelated optional parameters (json, zone), leaving the tool's full purpose ambiguous.

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 intended use is implied: call this when you need a lightweight citation/liveness check for a URL rather than stored page content. There is no explicit when-to-use/exclusion guidance or mention of when the optional json/zone parameters are appropriate.

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