diff --git a/.github/workflows/update-a2a-types.yml b/.github/workflows/update-a2a-types.yml
index af08b0a0..164135a5 100644
--- a/.github/workflows/update-a2a-types.yml
+++ b/.github/workflows/update-a2a-types.yml
@@ -58,7 +58,8 @@ jobs:
             --use-default-kwarg \
             --use-one-literal-as-default \
             --class-name A2A \
-            --use-standard-collections
+            --use-standard-collections \
+            --use-subclass-enum
           echo "Codegen finished."
 
       - name: Create Pull Request with Updates
diff --git a/development.md b/development.md
index d5d79b54..c1ecf029 100644
--- a/development.md
+++ b/development.md
@@ -17,5 +17,6 @@ uv run datamodel-codegen \
   --use-default-kwarg \
   --use-one-literal-as-default \
   --class-name A2A \
-  --use-standard-collections
+  --use-standard-collections \
+  --use-subclass-enum
 ```
diff --git a/src/a2a/types.py b/src/a2a/types.py
index 1cc4b299..b1aed42e 100644
--- a/src/a2a/types.py
+++ b/src/a2a/types.py
@@ -13,7 +13,7 @@ class A2A(RootModel[Any]):
     root: Any
 
 
-class In(Enum):
+class In(str, Enum):
     """
     The location of the API key. Valid values are "query", "header", or "cookie".
     """
@@ -484,7 +484,7 @@ class JSONRPCSuccessResponse(BaseModel):
     """
 
 
-class Role(Enum):
+class Role(str, Enum):
     """
     Message sender's role
     """
@@ -731,7 +731,7 @@ class TaskResubscriptionRequest(BaseModel):
     """
 
 
-class TaskState(Enum):
+class TaskState(str, Enum):
     """
     Represents the possible states of a Task.
     """
diff --git a/tests/test_types.py b/tests/test_types.py
index 99ccaa5f..d57ddda0 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -1487,3 +1487,12 @@ def test_a2a_error_validation_and_serialization() -> None:
     invalid_data: dict[str, Any] = {'code': -99999, 'message': 'Unknown error'}
     with pytest.raises(ValidationError):
         A2AError.model_validate(invalid_data)
+
+
+def test_subclass_enums() -> None:
+    """validate subtype enum types"""
+    assert "cookie" == In.cookie
+
+    assert "user" == Role.user
+
+    assert "working" == TaskState.working