Protein: Good for weight gain?

The limit in MFP (assuming you didn't change it) is set up so 15% of your calories come from protein (4 cal//gram protein). This is on the low end of the range that is considered healthy (10-30%). If you are strength training, you probably want to increase that.

Probably the best way is to change your percentage in MFP so that it matches a minimum protein intake of 0.75-1 gram of protein / lb of lean body weight while you are weight training.