A short brief is enough
Describe the workflow.
Tell us what happens now, what feels painful, and what a good result looks like. You do not need a product spec.
What happens today? How often, how much, and with which tools?
Slow, repetitive, error-prone, hard to find, or too much platform overhead?
A clear acceptance test makes the estimate better.
An intent range, not a commitment.
Sample files, constraints, references, or things the tool must never do.