All agents are parasites. They're a cancer on the game. People say "ohh they need them, contracts are soooo complicated!". Why are they complicated? Because they made them that way.
There is no reason whatsoever why contracts can't be simple, basic you get paid this much, bonus if you achieve this. Done. Then they can manage to sort that out themselves with their employers like all other grown adults in employment manage to do.
Then every single one of these parasites could be fecked off. Millions of millions of pounds a year staying in the game. Better world for everyone.