How to get bool result from async task<bool> function in C# - Error: Cannot implicitly convert type `void' to `bool'

I have created task function for validating my json file. Everything works fine until I didn't use the result. When I am trying to get the result from async task<bool> function it is showing error as Cannot implicitly convert 'void' to bool. My async function is as follows:

 private async Task<bool> MyValidationFunction(string json)
 {
     bool isValid = true;
     .......DOING MY VALIDATION STUFF.....
     return isValid;
 }

Calling this function from another function is as follows:

 public bool GetJsonAndValidate()
 {
      bool isValid = true;
      string jsonData = GetJson();
      //******* Here I am getting the error.
      bool isValid = MyValidationFunction(jsonData).Wait(); 
 }

When I am trying to call MyValidationFunction it is showing error as mention above. I have tried to get result by using Result property but it is throwing and error. My Class is just simple public class. I can do it with synchronous call but I need to have asynchronous call as MyValidationFunction get the result from database. If I didn't use the bool variable to capture the result, then it works fine. What I have missed out? How can I get bool result from my validation function?