This is the question that tells us most. There is no wrong answer and almost nobody has this solved.
The more specific you are about who uses it and what problem it solves, the more useful our reply will be.
No spec is completely normal. Producing one is what the Blueprint tier is for.
An honest range helps more than an optimistic one. It tells us which tier to scope against, and we'll say so if your budget and scope don't line up.
Goes straight to markus@prodclaw.ai. No mailing list, no automated sequence.