diff --git a/superset/annotation_layers/annotations/__init__.py b/superset/annotation_layers/annotations/__init__.py
new file mode 100644
index 0000000000..13a83393a9
--- /dev/null
+++ b/superset/annotation_layers/annotations/__init__.py
@@ -0,0 +1,16 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
diff --git a/superset/annotation_layers/annotations/api.py b/superset/annotation_layers/annotations/api.py
index bc39f5c3c1..4ddab2e19d 100644
--- a/superset/annotation_layers/annotations/api.py
+++ b/superset/annotation_layers/annotations/api.py
@@ -116,7 +116,9 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     openapi_spec_methods = openapi_spec_methods_override
 
     @staticmethod
-    def _apply_layered_relation_to_rison(layer_id: int, rison_parameters) -> None:
+    def _apply_layered_relation_to_rison(  # pylint: disable=invalid-name
+        layer_id: int, rison_parameters: Dict[str, Any]
+    ) -> None:
         if "filters" not in rison_parameters:
             rison_parameters["filters"] = []
         rison_parameters["filters"].append(
@@ -128,7 +130,9 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     @safe
     @permission_name("get")
     @rison(get_list_schema)
-    def get_list(self, pk: int, **kwargs: Dict[str, Any]) -> Response:
+    def get_list(  # pylint: disable=arguments-differ
+        self, pk: int, **kwargs: Dict[str, Any]
+    ) -> Response:
         """Get a list of annotations
         ---
         get:
@@ -169,7 +173,7 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
                           The result from the get list query
                         type: array
                         items:
-                          $ref: '#/components/schemas/{{self.__class__.__name__}}.get_list'  # noqa
+                          $ref: '#/components/schemas/{{self.__class__.__name__}}.get_list'  # pylint: disable=line-too-long
             400:
               $ref: '#/components/responses/400'
             401:
@@ -187,7 +191,9 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     @safe
     @permission_name("get")
     @rison(get_item_schema)
-    def get(self, pk: int, annotation_id: int, **kwargs: Dict[str, Any]) -> Response:
+    def get(  # pylint: disable=arguments-differ
+        self, pk: int, annotation_id: int, **kwargs: Dict[str, Any]
+    ) -> Response:
         """Get item from Model
         ---
         get:
@@ -242,7 +248,7 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     @safe
     @statsd_metrics
     @permission_name("post")
-    def post(self, pk: int) -> Response:
+    def post(self, pk: int) -> Response:  # pylint: disable=arguments-differ
         """Creates a new Annotation
         ---
         post:
@@ -308,7 +314,9 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     @safe
     @statsd_metrics
     @permission_name("put")
-    def put(self, pk: int, annotation_id: int) -> Response:
+    def put(  # pylint: disable=arguments-differ
+        self, pk: int, annotation_id: int
+    ) -> Response:
         """Updates an Annotation
         ---
         put:
@@ -379,7 +387,9 @@ class AnnotationRestApi(BaseSupersetModelRestApi):
     @safe
     @statsd_metrics
     @permission_name("delete")
-    def delete(self, pk: int, annotation_id: int) -> Response:
+    def delete(  # pylint: disable=arguments-differ
+        self, pk: int, annotation_id: int
+    ) -> Response:
         """Deletes an Annotation
         ---
         delete:
diff --git a/superset/annotation_layers/annotations/commands/update.py b/superset/annotation_layers/annotations/commands/update.py
index 2e6d568d44..1942bffa7f 100644
--- a/superset/annotation_layers/annotations/commands/update.py
+++ b/superset/annotation_layers/annotations/commands/update.py
@@ -70,15 +70,15 @@ class UpdateAnnotationCommand(BaseCommand):
             if not annotation_layer:
                 raise AnnotationLayerNotFoundError()
             self._properties["layer"] = annotation_layer
+
+            # Validate short descr uniqueness on this layer
+            if not AnnotationDAO.validate_update_uniqueness(
+                layer_id, short_descr, annotation_id=self._model_id,
+            ):
+                exceptions.append(AnnotationUniquenessValidationError())
         else:
             self._properties["layer"] = self._model.layer
 
-        # Validate short descr uniqueness on this layer
-        if not AnnotationDAO.validate_update_uniqueness(
-            layer_id, short_descr, annotation_id=self._model_id,
-        ):
-            exceptions.append(AnnotationUniquenessValidationError())
-
         # validate date time sanity
         start_dttm: Optional[datetime] = self._properties.get("start_dttm")
         end_dttm: Optional[datetime] = self._properties.get("end_dttm")
diff --git a/superset/annotation_layers/annotations/dao.py b/superset/annotation_layers/annotations/dao.py
index 293bc24709..50e4bcb29a 100644
--- a/superset/annotation_layers/annotations/dao.py
+++ b/superset/annotation_layers/annotations/dao.py
@@ -47,7 +47,7 @@ class AnnotationDAO(BaseDAO):
     @staticmethod
     def validate_update_uniqueness(
         layer_id: int, short_descr: str, annotation_id: Optional[int] = None
-    ):
+    ) -> bool:
         """
         Validate if this annotation short description is unique. `id` is optional
         and serves for validating on updates
diff --git a/superset/annotation_layers/annotations/schemas.py b/superset/annotation_layers/annotations/schemas.py
index 2ae0b91ccf..42af48d61b 100644
--- a/superset/annotation_layers/annotations/schemas.py
+++ b/superset/annotation_layers/annotations/schemas.py
@@ -14,7 +14,6 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-import json
 from typing import Union
 
 from marshmallow import fields, Schema, ValidationError