diff --git a/peps/pep-0746.rst b/peps/pep-0746.rst
index cfcb290db..cf94f3203 100644
--- a/peps/pep-0746.rst
+++ b/peps/pep-0746.rst
@@ -89,6 +89,13 @@ For example, to support a generic ``Gt`` metadata, one might write::
 Implementations may be generic and may use overloads that return ``Literal[True]`` or ``Literal[False]``
 to indicate if the metadata is valid for the given type.
 
+Implementations may raise a NotImplementedError if they cannot determine if the metadata is valid for the given type.
+Tools calling ``__supports_type__`` at runtime should catch this exception and treat it as if ``__supports_type__``
+was not present; they should not take this as an indication that the metadata is invalid for the type.
+
+Tools that use the metadata at runtime may choose to ignore the implementation of ``__supports_type__``; this PEP does not
+specify how the method should be used at runtime, only that it may be available for use.
+
 Backwards Compatibility
 =======================