Related question
How can I evaluate a potential AI partner without a large commitment?
Short answer
Book a custom training session for your team. Low cost, limited commitment, and a group setting that functions as an extended interview. Insist on training built around your business case rather than an off-the-shelf package, and watch carefully whether they can do it.
This is the lowest-risk evaluation move available to an executive, and it produces information no sales meeting will.
The trick is in the customization. Do not accept the standard package. Ask for training shaped around your actual business and your actual use cases. If they cannot do it, you have learned three things. They may not be built to communicate with people who are not technical. They may be steering you toward a rigid, prepackaged solution. Or, in the worst case, they cannot provide clear support for the tools they build.
You also get something of value regardless of what you conclude about the vendor. Your team learns something useful, and you get to watch how outside experts interact with your people, which tells you a great deal about how an implementation would go.
The additional screening questions are simple. Do they understand your business? Do they understand you? Not all developers are equal, and not all development firms bring any layer of business experience with them.