diff --git a/mlir/docs/OpDefinitions.md b/mlir/docs/OpDefinitions.md
--- a/mlir/docs/OpDefinitions.md
+++ b/mlir/docs/OpDefinitions.md
@@ -180,6 +180,10 @@
    shape of type. This is mostly used for convenience interface generation or
    interaction with other frameworks/translation.
 
+   All derived attributes should be materializable as an Attribute. That is,
+   even though they are not materialized, it should be possible to store as
+   an attribute.
+
 Both operands and attributes are specified inside the `dag`-typed `arguments`,
 led by `ins`:
 
diff --git a/mlir/include/mlir/IR/OpBase.td b/mlir/include/mlir/IR/OpBase.td
--- a/mlir/include/mlir/IR/OpBase.td
+++ b/mlir/include/mlir/IR/OpBase.td
@@ -1386,6 +1386,9 @@
 // DerivedAttr are attributes whose value is computed from properties
 // of the operation. They do not require additional storage and are
 // materialized as needed.
+// Note: All derived attributes should be materializable as an Attribute. E.g.,
+// do not used DerivedAttr for things that could not have been stored as
+// Attribute.
 class DerivedAttr<code ret, code b> : Attr<CPred<"true">, "derived attribute"> {
   let returnType = ret;
   code body = b;