When team augmentation is the right model
Team augmentation is the right model when you own the product direction and the engineering process, but need more experienced capacity than your team has. It fits a slipping roadmap, a skill gap, a team without senior review, or a key engineer who needs backup.
It is the wrong model when nobody inside the company can set priorities or review the work. In that case you need leadership first, which a part-time CTO can provide, or a partner that delivers a whole project for you, such as an MVP development company. The test is simple. If you can describe the work as tickets on your board, and someone on your side can choose between two designs, augmentation works. If you cannot, close the leadership gap first and add hands after that.

