diff --git a/docs/spec/directives.rst b/docs/spec/directives.rst
index 57f3c4b6e..3f8268c23 100644
--- a/docs/spec/directives.rst
+++ b/docs/spec/directives.rst
@@ -108,10 +108,16 @@ This approach may also be useful to handle import cycles.
 ``@no_type_check``
 ------------------
 
-To mark portions of the program that should not be covered by type
-hinting, you can use the ``@typing.no_type_check`` decorator on a class or function.
-Functions with this decorator should be treated as having
-no annotations.
+The ``@typing.no_type_check`` decorator may be supported by type checkers
+for functions and classes.
+
+If a type checker supports the ``no_type_check`` decorator for functions, it
+should suppress all type errors for the ``def`` statement and its body including
+any nested functions or classes. It should also ignore all parameter
+and return type annotations and treat the function as if it were unannotated.
+
+The behavior for the ``no_type_check`` decorator when applied to a class is
+left undefined by the typing spec at this time.
 
 Version and platform checking
 -----------------------------