The basics of each AGC parameter can be found below.

AGC - enable : this is to turn on and off AGC
AGC - targetPower : this is the normalized audio level which the algorithm will strive for
AGC - minGain : this is the most the audio signal will be brought down
AGC - maxGain : this is the most the audio signal will be amplified (The reason there is a maximum is to avoid heavily amplifying noise. Sometimes it is best for the talking party to simply speak up.)
AGC - attackRate / decayRate : this is how quickly the algorithm will try to adapt the audio (This is usually never set.)
AGC - speechThreshold : The goal for AGC is to only affect speech. This setting is the line that determines what is speech and what is not.

In general, only the targetPower setting is typically set by applications.