Ask yourself questions to determine whether the characteristics of the project fit an Agile project. For example, does the customer want to be involved in the development process and have input along the way? Is the customer willing to receive an initial product quickly and then enhanced versions over time? Is the delivery time frame a short one, a year tops? Or is it more of a multi-year project, very complex, very formal, bureaucratic, etc.? And so on. You get the picture. When you put the project to the test with these type of questions (and others you can think of), you will be able to answer yourself whether the project is suitable for Agile or not. Trust your instinct, trust what you have learned.