I still have not reached the top of the Agency tower, though I've seen YouTube videos of those that have. One actually drove the Agency SUV (with four star driving skill) straight up the side of the tower. Another did it on foot with four star agility.
I don't have four star agility, but do have four star driving skills, so I think I will make my next attempt in the SUV.
After an unsuccessful attempt Saturday to scale the Agency tower, I directed my attention to the next Shai-Gen general and took him down handily.
Every general has a finite number of guards, and in his HQ alcoves or other bits of cover where an agent can hide to recharge his shields and health. You can keep killing the guards and recharging until no more come, then take on the general alone.
Don't get killed while doing this, or quit the game; either will reset the general and give him a fresh supply of guards.
Finally, to kill generals I like to kick them to death. This might have something to do with my maxed out strength skill.
Sunday I tried scaling the tower with the SUV, and discovered that climbing walls with that vehicle takes more finesse than I have right now. So I switched to assaulting generals and took down another.
Next I shall spend some time learning to climb buildings with the SUV.