It is not an AGC it is an antenna attenuator and good if you go to you will lose from 2 to 3 points S in reception, the system is not bypassable, even when turned off the MOSFET remains inserted in series with the antenna and, as in all "attenuators "automatic (look at some articles on PIN diodes), there is a residual attenuation that cannot be eliminated ... if you don't mind losing S points from your receiver, use it, but don't call it" AGC "it is doesn't and it doesn't check any "gain", simply "attenuates the antenna input signal".
