Main language: calls to functions not evaluated (delayed expression)

Let's say our current context is formed by the default context plus the following single function:

F(x_, y_) := x + y;

An expected use of F It is this:

F(0, 1)

Consider two examples of unexpected uses. One with the wrong name, the other with an incorrect number of arguments:

G(0, 1)
F(0)

Both are valid Mathematica expressions, however, I am not interested in them in this context.

How can I make sure there are no function calls that are not evaluated (delayed expressions)?

  1. Is there a function that takes an expression and affirms this requirement?
  2. Is there a function that affirms this about all the following expressions in context?