Coutinho has battled for form this season, though was on the scoresheet for their 5-1 Champions League rout of Lyon last night.
But Tostao told Sport: "Coutinho does not play well because he is competing with (Ousmane) Dembélé. He has little confidence because he was the star of Brazil and Liverpool, at Barça, it is not the case.
"He must assume that he plays with players superior to him. Coutinho must improve, but Barca must assume that Coutinho is not Neymar. Coutinho is a good player, but he is not a super craque like Neymar, (Kylian) Mbappé or (Eden) Hazard. He is a great player, but he generates too high expectations and he is not able to justify them, which offers a negative dynamic."