Anything that isn't explicitly enforced by contract is vulnerable to misunderstandings. It's doing your teammates a great service, and reducing everyone's effort, by eliminating ambiguity and enforcing information flow by design.

This assumes that the module has been given a well-defined, stable description (the interface in the sense of information hiding).

Explicit interfaces are preferable, even if it places greater demand on library authors to design both their components and their style interfaces with these things in mind.