The two obvious answers are to 1) network your ass off, and 2) make sure the product blows users away in both quality and support.

If you have any inroads with your sellers, go to where they are and convince them that your tool is going to make everyone's projects better. If you can't convincingly make that argument, work on improving your product and/or confidence before continuing.

If you have competition, monitor for complaints about their products. See what frustrates their users and make sure you're not making the same mistakes in your product. If your product offers a clear solution to that problem and the user is complaining publicly (e.g. on Twitter) then offer the solution and incentivize the switch.

If you can't sell direct to customers, then you'll probably want to target industry events where your sellers attend. You could sponsor MS-focused conferences and find a way to display convincing case studies and/or let people see the tool in action as a selling point.

Most importantly, remember that clients don't hire fancy tech; they hire solutions to problems. In the first ten seconds, no one cares what tech stack it was built in, how clever the algorithms are, or anything else about what makes it work — they only care about whether their problems can be solved.

Show them how your tool will solve their problems faster and easier than anything they've ever tried before, and with fewer painful side effects.

Good luck!