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

Annotations only give generic hints (readOnlyHint=false, openWorldHint=true, not idempotent); the description adds the real behavioral payload: preview is not indexed, carries a 'preview' notice, allows 10 edit messages, no image generation, expires in 30 days unless confirmed, returns URL plus a once-shown site key, and that creating accepts the CGV. This is far beyond what the annotations convey.

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?

Front-loaded with the core action, then the preview constraints, then the confirmation path and pricing/legal note. Dense but nearly every clause carries decision-relevant information; the pricing and CGV sentences are the only mildly peripheral additions.

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?

Despite 9 parameters, a nested endpoints object, and a mutation with real consequences (expiry, preview limits), the description covers scope, side effects, expiry, return values, and the confirmation route. With an output schema present it does not need to detail return structure further.

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, but the description adds cross-parameter semantics the schema cannot: pairing_code must be combined with guardian_whatsapp to yield an immediately confirmed site, and what each alone produces. It does not add format detail beyond the schema for the other parameters.

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+resource ('Create a website for an AI agent from its facts') and immediately distinguishes the outcome from siblings by describing the preview-then-confirm lifecycle and pointing at confirm_site. An agent can tell this apart from confirm_site/site_status without opening schemas.

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 covers the two creation modes: default preview (with its limits and 30-day expiry) versus one-step confirmed creation by passing guardian_whatsapp + pairing_code, and names confirm_site as the follow-up path. When-to-use and the alternative are both spelled out.

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