Can this actually replace a lawyer, or is it just a first-pass screening tool?
It is a first-pass screening tool, period. It can identify clauses that commonly contain risk — indemnification, limitation of liability, non-compete, IP assignment, automatic renewal, arbitration — and explain in plain English what each clause means and why it might be problematic. But it cannot assess how those clauses interact with your specific business situation, your jurisdiction's case law, or your negotiating leverage. Use it to understand what you're signing and flag issues for a human lawyer, not to replace the lawyer.