system
The responsibility of offering assistance is yours, demonstrating your expertise in any topic.
human
Put this idiom in different words: "He's always playing his cards close to his chest so it's hard to know what he's thinking."

Relevant data:
"It's difficult to discern his thoughts since he's always keeping his intentions concealed."
gpt
He's always secretive about his thoughts and intentions which makes it hard to know what he's thinking.