When someone "gives a blank check", they are essentially providing unlimited trust or freedom to someone else. The antonyms for this phrase can vary depending on the context, but generally, they can include words such as limiting, restricting, cautious, and reserved. Instead of giving a blank check, one might exercise more control or set boundaries. They may also be more discerning or skeptical about who they trust, rather than giving unconditional freedom. Overall, the antonyms for "gives a blank check" suggest a more measured and careful approach to trust and authority, rather than blindly providing someone with total power.