The Problem Discovery Tool helps you prepare for and conduct "Problem Interviews," a specific type of interview intended to help you discover or validate that you have identified a real problem, unmet need, or "job to be done." If done well, they can also help you qualify how valuable or important a solution to the problem or unmet need may be. You may have identified a real problem, but if it's not a big problem for the customer, the hurdle of adopting your potential solution will likely need to be very low, or the value captured for your potential solution may not be that great.
Innovation is only valuable if it addresses a problem or an unmet need. The better you understand an unmet need, the better your chance of developing a good solution. You don't want to waste time and effort working on a solution to a problem that doesn't exist or for which the current alternatives are good enough. Understanding how important an unmet need is in the eye of your potential customer can help you determine how much value your solution might be able to capture.
However, there's much more to learn in a Problem Interview than just the problem itself. How are they dealing with that problem today? What alternatives have they tried or considered, and what are their pros and cons? This can help you understand Competing Alternatives and the comparative criteria important to your potential customer. You may also want to explore how your audience might try to find a solution. This can provide important insights about how you may want to deploy and promote your solution in a way that aligns with your audience's natural behavior.