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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is covered. The description adds real behavioral context beyond them: the operation can fail for anonymous demo pages when editToken is missing, and the token must come from the create result. It does not discuss caching or expiry of the returned URL, which is the main remaining unknown.

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?

Three short sentences, front-loaded with the return value, then the routing advice, then the failure condition. No filler; each sentence changes agent behavior.

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?

With an output schema present, return values need not be explained, and the description covers the two things that matter for correct invocation: when not to call it and the editToken requirement for anonymous pages. Complete for a two-parameter read tool.

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% and the schema already documents editToken as 'Required for anonymous demo pages.' The description paraphrases that same constraint rather than adding format, sourcing, or edge-case detail, so the baseline 3 applies.

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 the current preview URL for a page') and immediately positions itself against siblings page_create and page_create_from_brief, which already return a previewUrl. An agent can tell why this tool exists and when the others make it redundant.

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?

Explicitly says 'You usually do not need this' and names the two alternatives that supply previewUrl already. It also gives the one condition that forces this call — anonymous demo pages needing editToken — plus the failure mode if that token is omitted.

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