diff --git a/moto/resourcegroups/exceptions.py b/moto/resourcegroups/exceptions.py
index 17e17c4a2..9a74f4651 100644
--- a/moto/resourcegroups/exceptions.py
+++ b/moto/resourcegroups/exceptions.py
@@ -4,5 +4,5 @@ from moto.core.exceptions import JsonRESTError
 class BadRequestException(JsonRESTError):
     code = 400
 
-    def __init__(self, message, **kwargs):
+    def __init__(self, message: str):
         super().__init__(error_type="BadRequestException", message=message)
diff --git a/moto/resourcegroups/models.py b/moto/resourcegroups/models.py
index 76a06ce6f..0dd363fad 100644
--- a/moto/resourcegroups/models.py
+++ b/moto/resourcegroups/models.py
@@ -1,4 +1,4 @@
-from builtins import str
+from typing import Any, Dict, List, Optional
 
 import json
 import re
@@ -10,14 +10,14 @@ from .exceptions import BadRequestException
 class FakeResourceGroup(BaseModel):
     def __init__(
         self,
-        account_id,
-        name,
-        resource_query,
-        description=None,
-        tags=None,
-        configuration=None,
+        account_id: str,
+        name: str,
+        resource_query: Dict[str, str],
+        description: Optional[str] = None,
+        tags: Optional[Dict[str, str]] = None,
+        configuration: Optional[List[Dict[str, Any]]] = None,
     ):
-        self.errors = []
+        self.errors: List[str] = []
         description = description or ""
         tags = tags or {}
         if self._validate_description(value=description):
@@ -33,10 +33,10 @@ class FakeResourceGroup(BaseModel):
         self.configuration = configuration
 
     @staticmethod
-    def _format_error(key, value, constraint):
+    def _format_error(key: str, value: Any, constraint: str) -> str:  # type: ignore[misc]
         return f"Value '{value}' at '{key}' failed to satisfy constraint: {constraint}"
 
-    def _raise_errors(self):
+    def _raise_errors(self) -> None:
         if self.errors:
             errors_len = len(self.errors)
             plural = "s" if len(self.errors) > 1 else ""
@@ -45,7 +45,7 @@ class FakeResourceGroup(BaseModel):
                 f"{errors_len} validation error{plural} detected: {errors}"
             )
 
-    def _validate_description(self, value):
+    def _validate_description(self, value: str) -> bool:
         errors = []
         if len(value) > 511:
             errors.append(
@@ -68,7 +68,7 @@ class FakeResourceGroup(BaseModel):
             return False
         return True
 
-    def _validate_name(self, value):
+    def _validate_name(self, value: str) -> bool:
         errors = []
         if len(value) > 128:
             errors.append(
@@ -92,7 +92,7 @@ class FakeResourceGroup(BaseModel):
             return False
         return True
 
-    def _validate_resource_query(self, value):
+    def _validate_resource_query(self, value: Dict[str, str]) -> bool:
         if not value:
             return True
         errors = []
@@ -117,7 +117,7 @@ class FakeResourceGroup(BaseModel):
             return False
         return True
 
-    def _validate_tags(self, value):
+    def _validate_tags(self, value: Dict[str, str]) -> bool:
         errors = []
         # AWS only outputs one error for all keys and one for all values.
         error_keys = None
@@ -160,59 +160,59 @@ class FakeResourceGroup(BaseModel):
         return True
 
     @property
-    def description(self):
+    def description(self) -> str:
         return self._description
 
     @description.setter
-    def description(self, value):
+    def description(self, value: str) -> None:
         if not self._validate_description(value=value):
             self._raise_errors()
         self._description = value
 
     @property
-    def name(self):
+    def name(self) -> str:
         return self._name
 
     @name.setter
-    def name(self, value):
+    def name(self, value: str) -> None:
         if not self._validate_name(value=value):
             self._raise_errors()
         self._name = value
 
     @property
-    def resource_query(self):
+    def resource_query(self) -> Dict[str, str]:
         return self._resource_query
 
     @resource_query.setter
-    def resource_query(self, value):
+    def resource_query(self, value: Dict[str, str]) -> None:
         if not self._validate_resource_query(value=value):
             self._raise_errors()
         self._resource_query = value
 
     @property
-    def tags(self):
+    def tags(self) -> Dict[str, str]:
         return self._tags
 
     @tags.setter
-    def tags(self, value):
+    def tags(self, value: Dict[str, str]) -> None:
         if not self._validate_tags(value=value):
             self._raise_errors()
         self._tags = value
 
 
 class ResourceGroups:
-    def __init__(self):
-        self.by_name = {}
-        self.by_arn = {}
+    def __init__(self) -> None:
+        self.by_name: Dict[str, FakeResourceGroup] = {}
+        self.by_arn: Dict[str, FakeResourceGroup] = {}
 
-    def __contains__(self, item):
+    def __contains__(self, item: str) -> bool:
         return item in self.by_name
 
-    def append(self, resource_group):
+    def append(self, resource_group: FakeResourceGroup) -> None:
         self.by_name[resource_group.name] = resource_group
         self.by_arn[resource_group.arn] = resource_group
 
-    def delete(self, name):
+    def delete(self, name: str) -> FakeResourceGroup:
         group = self.by_name[name]
         del self.by_name[name]
         del self.by_arn[group.arn]
@@ -220,12 +220,12 @@ class ResourceGroups:
 
 
 class ResourceGroupsBackend(BaseBackend):
-    def __init__(self, region_name, account_id):
+    def __init__(self, region_name: str, account_id: str):
         super().__init__(region_name, account_id)
         self.groups = ResourceGroups()
 
     @staticmethod
-    def _validate_resource_query(resource_query):
+    def _validate_resource_query(resource_query: Dict[str, str]) -> None:
         if not resource_query:
             return
         query_type = resource_query["Type"]
@@ -294,14 +294,19 @@ class ResourceGroupsBackend(BaseBackend):
                         )
 
     @staticmethod
-    def _validate_tags(tags):
+    def _validate_tags(tags: Dict[str, str]) -> None:
         for tag in tags:
             if tag.lower().startswith("aws:"):
                 raise BadRequestException("Tag keys must not start with 'aws:'")
 
     def create_group(
-        self, name, resource_query, description=None, tags=None, configuration=None
-    ):
+        self,
+        name: str,
+        resource_query: Dict[str, str],
+        description: Optional[str] = None,
+        tags: Optional[Dict[str, str]] = None,
+        configuration: Optional[List[Dict[str, Any]]] = None,
+    ) -> FakeResourceGroup:
         tags = tags or {}
         group = FakeResourceGroup(
             account_id=self.account_id,
@@ -320,48 +325,55 @@ class ResourceGroupsBackend(BaseBackend):
         self.groups.append(group)
         return group
 
-    def delete_group(self, group_name):
+    def delete_group(self, group_name: str) -> FakeResourceGroup:
         return self.groups.delete(name=group_name)
 
-    def get_group(self, group_name):
+    def get_group(self, group_name: str) -> FakeResourceGroup:
         return self.groups.by_name[group_name]
 
-    def get_tags(self, arn):
+    def get_tags(self, arn: str) -> Dict[str, str]:
         return self.groups.by_arn[arn].tags
 
-    def list_groups(self):
+    def list_groups(self) -> Dict[str, FakeResourceGroup]:
         """
         Pagination or the Filters-parameter is not yet implemented
         """
         return self.groups.by_name
 
-    def tag(self, arn, tags):
+    def tag(self, arn: str, tags: Dict[str, str]) -> None:
         all_tags = self.groups.by_arn[arn].tags
         all_tags.update(tags)
         self._validate_tags(all_tags)
         self.groups.by_arn[arn].tags = all_tags
 
-    def untag(self, arn, keys):
+    def untag(self, arn: str, keys: List[str]) -> None:
         group = self.groups.by_arn[arn]
         for key in keys:
             del group.tags[key]
 
-    def update_group(self, group_name, description=None):
+    def update_group(
+        self, group_name: str, description: Optional[str] = None
+    ) -> FakeResourceGroup:
         if description:
             self.groups.by_name[group_name].description = description
         return self.groups.by_name[group_name]
 
-    def update_group_query(self, group_name, resource_query):
+    def update_group_query(
+        self, group_name: str, resource_query: Dict[str, str]
+    ) -> FakeResourceGroup:
         self._validate_resource_query(resource_query)
         self.groups.by_name[group_name].resource_query = resource_query
         return self.groups.by_name[group_name]
 
-    def get_group_configuration(self, group_name):
-        group = self.groups.by_name.get(group_name)
-        configuration = group.configuration
-        return configuration
+    def get_group_configuration(
+        self, group_name: str
+    ) -> Optional[List[Dict[str, Any]]]:
+        group = self.groups.by_name[group_name]
+        return group.configuration
 
-    def put_group_configuration(self, group_name, configuration):
+    def put_group_configuration(
+        self, group_name: str, configuration: List[Dict[str, Any]]
+    ) -> FakeResourceGroup:
         self.groups.by_name[group_name].configuration = configuration
         return self.groups.by_name[group_name]
 
diff --git a/moto/resourcegroups/responses.py b/moto/resourcegroups/responses.py
index 9a076f867..4057ba4f4 100644
--- a/moto/resourcegroups/responses.py
+++ b/moto/resourcegroups/responses.py
@@ -3,18 +3,18 @@ import json
 from urllib.parse import unquote
 
 from moto.core.responses import BaseResponse
-from .models import resourcegroups_backends
+from .models import resourcegroups_backends, ResourceGroupsBackend
 
 
 class ResourceGroupsResponse(BaseResponse):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__(service_name="resource-groups")
 
     @property
-    def resourcegroups_backend(self):
+    def resourcegroups_backend(self) -> ResourceGroupsBackend:
         return resourcegroups_backends[self.current_account][self.region]
 
-    def create_group(self):
+    def create_group(self) -> str:
         name = self._get_param("Name")
         description = self._get_param("Description")
         resource_query = self._get_param("ResourceQuery")
@@ -40,7 +40,7 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def delete_group(self):
+    def delete_group(self) -> str:
         group_name = self._get_param("GroupName") or self._get_param("Group")
         group = self.resourcegroups_backend.delete_group(group_name=group_name)
         return json.dumps(
@@ -53,7 +53,7 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def get_group(self):
+    def get_group(self) -> str:
         group_name = self._get_param("GroupName")
         group = self.resourcegroups_backend.get_group(group_name=group_name)
         return json.dumps(
@@ -66,7 +66,7 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def get_group_query(self):
+    def get_group_query(self) -> str:
         group_name = self._get_param("GroupName")
         group_arn = self._get_param("Group")
         if group_arn and not group_name:
@@ -81,18 +81,18 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def get_tags(self):
+    def get_tags(self) -> str:
         arn = unquote(self._get_param("Arn"))
         return json.dumps(
             {"Arn": arn, "Tags": self.resourcegroups_backend.get_tags(arn=arn)}
         )
 
-    def list_group_resources(self):
+    def list_group_resources(self) -> None:
         raise NotImplementedError(
             "ResourceGroups.list_group_resources is not yet implemented"
         )
 
-    def list_groups(self):
+    def list_groups(self) -> str:
         groups = self.resourcegroups_backend.list_groups()
         return json.dumps(
             {
@@ -112,12 +112,12 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def search_resources(self):
+    def search_resources(self) -> None:
         raise NotImplementedError(
             "ResourceGroups.search_resources is not yet implemented"
         )
 
-    def tag(self):
+    def tag(self) -> str:
         arn = unquote(self._get_param("Arn"))
         tags = self._get_param("Tags")
         if arn not in self.resourcegroups_backend.groups.by_arn:
@@ -127,7 +127,7 @@ class ResourceGroupsResponse(BaseResponse):
         self.resourcegroups_backend.tag(arn=arn, tags=tags)
         return json.dumps({"Arn": arn, "Tags": tags})
 
-    def untag(self):
+    def untag(self) -> str:
         arn = unquote(self._get_param("Arn"))
         keys = self._get_param("Keys")
         if arn not in self.resourcegroups_backend.groups.by_arn:
@@ -137,7 +137,7 @@ class ResourceGroupsResponse(BaseResponse):
         self.resourcegroups_backend.untag(arn=arn, keys=keys)
         return json.dumps({"Arn": arn, "Keys": keys})
 
-    def update_group(self):
+    def update_group(self) -> str:
         group_name = self._get_param("GroupName")
         description = self._get_param("Description", "")
         group = self.resourcegroups_backend.update_group(
@@ -153,7 +153,7 @@ class ResourceGroupsResponse(BaseResponse):
             }
         )
 
-    def update_group_query(self):
+    def update_group_query(self) -> str:
         group_name = self._get_param("GroupName")
         resource_query = self._get_param("ResourceQuery")
         group_arn = self._get_param("Group")
@@ -166,14 +166,14 @@ class ResourceGroupsResponse(BaseResponse):
             {"GroupQuery": {"GroupName": group.name, "ResourceQuery": resource_query}}
         )
 
-    def get_group_configuration(self):
+    def get_group_configuration(self) -> str:
         group_name = self._get_param("Group")
         configuration = self.resourcegroups_backend.get_group_configuration(
             group_name=group_name
         )
         return json.dumps({"GroupConfiguration": {"Configuration": configuration}})
 
-    def put_group_configuration(self):
+    def put_group_configuration(self) -> str:
         group_name = self._get_param("Group")
         configuration = self._get_param("Configuration")
         self.resourcegroups_backend.put_group_configuration(
diff --git a/moto/resourcegroupstaggingapi/models.py b/moto/resourcegroupstaggingapi/models.py
index 4abb7893f..d7e77938e 100644
--- a/moto/resourcegroupstaggingapi/models.py
+++ b/moto/resourcegroupstaggingapi/models.py
@@ -1,19 +1,20 @@
+from typing import Any, Dict, List, Iterator, Optional, Tuple
 from moto.core import BaseBackend, BackendDict
 from moto.core.exceptions import RESTError
 from moto.moto_api._internal import mock_random
 
-from moto.s3 import s3_backends
+from moto.s3.models import s3_backends, S3Backend
 from moto.ec2 import ec2_backends
-from moto.elb import elb_backends
-from moto.elbv2 import elbv2_backends
-from moto.kinesis import kinesis_backends
-from moto.kms import kms_backends
-from moto.rds import rds_backends
-from moto.glacier import glacier_backends
-from moto.redshift import redshift_backends
-from moto.emr import emr_backends
-from moto.awslambda import lambda_backends
-from moto.ecs import ecs_backends
+from moto.elb.models import elb_backends, ELBBackend
+from moto.elbv2.models import elbv2_backends, ELBv2Backend
+from moto.kinesis.models import kinesis_backends, KinesisBackend
+from moto.kms.models import kms_backends, KmsBackend
+from moto.rds.models import rds_backends, RDSBackend
+from moto.glacier.models import glacier_backends, GlacierBackend
+from moto.redshift.models import redshift_backends, RedshiftBackend
+from moto.emr.models import emr_backends, ElasticMapReduceBackend
+from moto.awslambda.models import lambda_backends, LambdaBackend
+from moto.ecs.models import ecs_backends, EC2ContainerServiceBackend
 
 # Left: EC2 ElastiCache RDS ELB CloudFront WorkSpaces Lambda EMR Glacier Kinesis Redshift Route53
 # StorageGateway DynamoDB MachineLearning ACM DirectConnect DirectoryService CloudHSM
@@ -21,106 +22,74 @@ from moto.ecs import ecs_backends
 
 
 class ResourceGroupsTaggingAPIBackend(BaseBackend):
-    def __init__(self, region_name, account_id):
+    def __init__(self, region_name: str, account_id: str):
         super().__init__(region_name, account_id)
 
-        self._pages = {}
+        self._pages: Dict[str, Any] = {}
         # Like 'someuuid': {'gen': <generator>, 'misc': None}
         # Misc is there for peeking from a generator and it cant
         # fit in the current request. As we only store generators
         # theres not really any point to clean up
 
     @property
-    def s3_backend(self):
-        """
-        :rtype: moto.s3.models.S3Backend
-        """
+    def s3_backend(self) -> S3Backend:
         return s3_backends[self.account_id]["global"]
 
     @property
-    def ec2_backend(self):
-        """
-        :rtype: moto.ec2.models.EC2Backend
-        """
+    def ec2_backend(self) -> Any:  # type: ignore[misc]
         return ec2_backends[self.account_id][self.region_name]
 
     @property
-    def elb_backend(self):
-        """
-        :rtype: moto.elb.models.ELBBackend
-        """
+    def elb_backend(self) -> ELBBackend:
         return elb_backends[self.account_id][self.region_name]
 
     @property
-    def elbv2_backend(self):
-        """
-        :rtype: moto.elbv2.models.ELBv2Backend
-        """
+    def elbv2_backend(self) -> ELBv2Backend:
         return elbv2_backends[self.account_id][self.region_name]
 
     @property
-    def kinesis_backend(self):
-        """
-        :rtype: moto.kinesis.models.KinesisBackend
-        """
+    def kinesis_backend(self) -> KinesisBackend:
         return kinesis_backends[self.account_id][self.region_name]
 
     @property
-    def kms_backend(self):
-        """
-        :rtype: moto.kms.models.KmsBackend
-        """
+    def kms_backend(self) -> KmsBackend:
         return kms_backends[self.account_id][self.region_name]
 
     @property
-    def rds_backend(self):
-        """
-        :rtype: moto.rds.models.RDSBackend
-        """
+    def rds_backend(self) -> RDSBackend:
         return rds_backends[self.account_id][self.region_name]
 
     @property
-    def glacier_backend(self):
-        """
-        :rtype: moto.glacier.models.GlacierBackend
-        """
+    def glacier_backend(self) -> GlacierBackend:
         return glacier_backends[self.account_id][self.region_name]
 
     @property
-    def emr_backend(self):
-        """
-        :rtype: moto.emr.models.ElasticMapReduceBackend
-        """
+    def emr_backend(self) -> ElasticMapReduceBackend:
         return emr_backends[self.account_id][self.region_name]
 
     @property
-    def redshift_backend(self):
-        """
-        :rtype: moto.redshift.models.RedshiftBackend
-        """
+    def redshift_backend(self) -> RedshiftBackend:
         return redshift_backends[self.account_id][self.region_name]
 
     @property
-    def lambda_backend(self):
-        """
-        :rtype: moto.awslambda.models.LambdaBackend
-        """
+    def lambda_backend(self) -> LambdaBackend:
         return lambda_backends[self.account_id][self.region_name]
 
     @property
-    def ecs_backend(self):
-        """
-        :rtype: moto.ecs.models.EcsnBackend
-        """
+    def ecs_backend(self) -> EC2ContainerServiceBackend:
         return ecs_backends[self.account_id][self.region_name]
 
-    def _get_resources_generator(self, tag_filters=None, resource_type_filters=None):
+    def _get_resources_generator(
+        self,
+        tag_filters: Optional[List[Dict[str, Any]]] = None,
+        resource_type_filters: Optional[List[str]] = None,
+    ) -> Iterator[Dict[str, Any]]:
         # Look at
         # https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html
 
         # TODO move these to their respective backends
         filters = []
-        for tag_filter_dict in tag_filters:
+        for tag_filter_dict in tag_filters:  # type: ignore
             values = tag_filter_dict.get("Values", [])
             if len(values) == 0:
                 # Check key matches
@@ -128,36 +97,38 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
             elif len(values) == 1:
                 # Check its exactly the same as key, value
                 filters.append(
-                    lambda t, v, key=tag_filter_dict["Key"], value=values[0]: t == key
+                    lambda t, v, key=tag_filter_dict["Key"], value=values[0]: t == key  # type: ignore
                     and v == value
                 )
             else:
                 # Check key matches and value is one of the provided values
                 filters.append(
-                    lambda t, v, key=tag_filter_dict["Key"], vl=values: t == key
+                    lambda t, v, key=tag_filter_dict["Key"], vl=values: t == key  # type: ignore
                     and v in vl
                 )
 
-        def tag_filter(tag_list):
+        def tag_filter(tag_list: List[Dict[str, str]]) -> bool:
             result = []
             if tag_filters:
                 for f in filters:
                     temp_result = []
                     for tag in tag_list:
-                        f_result = f(tag["Key"], tag["Value"])
+                        f_result = f(tag["Key"], tag["Value"])  # type: ignore
                         temp_result.append(f_result)
                     result.append(any(temp_result))
                 return all(result)
             else:
                 return True
 
-        def format_tags(tags):
+        def format_tags(tags: Dict[str, str]) -> List[Dict[str, str]]:
             result = []
             for key, value in tags.items():
                 result.append({"Key": key, "Value": value})
             return result
 
-        def format_tag_keys(tags, keys):
+        def format_tag_keys(
+            tags: List[Dict[str, str]], keys: List[str]
+        ) -> List[Dict[str, str]]:
             result = []
             for tag in tags:
                 result.append({"Key": tag[keys[0]], "Value": tag[keys[1]]})
@@ -200,7 +171,7 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
 
         if not resource_type_filters or "ecs:cluster" in resource_type_filters:
             for cluster in self.ecs_backend.clusters.values():
-                tags = format_tag_keys(cluster.tags, ["key", "value"])
+                tags = format_tag_keys(cluster.tags, ["key", "value"])  # type: ignore[arg-type]
                 if not tag_filter(tags):
                     continue
                 yield {"ResourceARN": f"{cluster.arn}", "Tags": tags}
@@ -222,9 +193,8 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
             for ami in self.ec2_backend.amis.values():
                 tags = format_tags(self.ec2_backend.tags.get(ami.id, {}))
 
-                if not tags or not tag_filter(
-                    tags
-                ):  # Skip if no tags, or invalid filter
+                if not tags or not tag_filter(tags):
+                    # Skip if no tags, or invalid filter
                     continue
                 yield {
                     "ResourceARN": f"arn:aws:ec2:{self.region_name}::image/{ami.id}",
@@ -241,9 +211,8 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
                 for instance in reservation.instances:
                     tags = format_tags(self.ec2_backend.tags.get(instance.id, {}))
 
-                    if not tags or not tag_filter(
-                        tags
-                    ):  # Skip if no tags, or invalid filter
+                    if not tags or not tag_filter(tags):
+                        # Skip if no tags, or invalid filter
                         continue
                     yield {
                         "ResourceARN": f"arn:aws:ec2:{self.region_name}::instance/{instance.id}",
@@ -259,9 +228,8 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
             for eni in self.ec2_backend.enis.values():
                 tags = format_tags(self.ec2_backend.tags.get(eni.id, {}))
 
-                if not tags or not tag_filter(
-                    tags
-                ):  # Skip if no tags, or invalid filter
+                if not tags or not tag_filter(tags):
+                    # Skip if no tags, or invalid filter
                     continue
                 yield {
                     "ResourceARN": f"arn:aws:ec2:{self.region_name}::network-interface/{eni.id}",
@@ -280,9 +248,8 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
                 for sg in vpc.values():
                     tags = format_tags(self.ec2_backend.tags.get(sg.id, {}))
 
-                    if not tags or not tag_filter(
-                        tags
-                    ):  # Skip if no tags, or invalid filter
+                    if not tags or not tag_filter(tags):
+                        # Skip if no tags, or invalid filter
                         continue
                     yield {
                         "ResourceARN": f"arn:aws:ec2:{self.region_name}::security-group/{sg.id}",
@@ -298,9 +265,8 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
             for snapshot in self.ec2_backend.snapshots.values():
                 tags = format_tags(self.ec2_backend.tags.get(snapshot.id, {}))
 
-                if not tags or not tag_filter(
-                    tags
-                ):  # Skip if no tags, or invalid filter
+                if not tags or not tag_filter(tags):
+                    # Skip if no tags, or invalid filter
                     continue
                 yield {
                     "ResourceARN": f"arn:aws:ec2:{self.region_name}::snapshot/{snapshot.id}",
@@ -382,12 +348,12 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
             or "rds" in resource_type_filters
             or "rds:cluster" in resource_type_filters
         ):
-            for cluster in self.rds_backend.clusters.values():
-                tags = cluster.get_tags()
+            for rds_cluster in self.rds_backend.clusters.values():
+                tags = rds_cluster.get_tags()
                 if not tags or not tag_filter(tags):
                     continue
                 yield {
-                    "ResourceARN": cluster.db_cluster_arn,
+                    "ResourceARN": rds_cluster.db_cluster_arn,
                     "Tags": tags,
                 }
 
@@ -487,7 +453,7 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
                     "Tags": tags,
                 }
 
-    def _get_tag_keys_generator(self):
+    def _get_tag_keys_generator(self) -> Iterator[str]:
         # Look at
         # https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html
 
@@ -498,7 +464,7 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
                 yield key
 
         # EC2 tags
-        def get_ec2_keys(res_id):
+        def get_ec2_keys(res_id: str) -> List[Dict[str, str]]:
             result = []
             for key in self.ec2_backend.tags.get(res_id, {}):
                 result.append(key)
@@ -506,18 +472,18 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
 
         # EC2 AMI, resource type ec2:image
         for ami in self.ec2_backend.amis.values():
-            for key in get_ec2_keys(ami.id):
+            for key in get_ec2_keys(ami.id):  # type: ignore[assignment]
                 yield key
 
         # EC2 Instance, resource type ec2:instance
         for reservation in self.ec2_backend.reservations.values():
             for instance in reservation.instances:
-                for key in get_ec2_keys(instance.id):
+                for key in get_ec2_keys(instance.id):  # type: ignore[assignment]
                     yield key
 
         # EC2 NetworkInterface, resource type ec2:network-interface
         for eni in self.ec2_backend.enis.values():
-            for key in get_ec2_keys(eni.id):
+            for key in get_ec2_keys(eni.id):  # type: ignore[assignment]
                 yield key
 
         # TODO EC2 ReservedInstance
@@ -525,22 +491,22 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
         # EC2 SecurityGroup, resource type ec2:security-group
         for vpc in self.ec2_backend.groups.values():
             for sg in vpc.values():
-                for key in get_ec2_keys(sg.id):
+                for key in get_ec2_keys(sg.id):  # type: ignore[assignment]
                     yield key
 
         # EC2 Snapshot, resource type ec2:snapshot
         for snapshot in self.ec2_backend.snapshots.values():
-            for key in get_ec2_keys(snapshot.id):
+            for key in get_ec2_keys(snapshot.id):  # type: ignore[assignment]
                 yield key
 
         # TODO EC2 SpotInstanceRequest
 
         # EC2 Volume, resource type ec2:volume
         for volume in self.ec2_backend.volumes.values():
-            for key in get_ec2_keys(volume.id):
+            for key in get_ec2_keys(volume.id):  # type: ignore[assignment]
                 yield key
 
-    def _get_tag_values_generator(self, tag_key):
+    def _get_tag_values_generator(self, tag_key: str) -> Iterator[str]:
         # Look at
         # https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html
 
@@ -552,7 +518,7 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
                     yield value
 
         # EC2 tags
-        def get_ec2_values(res_id):
+        def get_ec2_values(res_id: str) -> List[Dict[str, str]]:
             result = []
             for key, value in self.ec2_backend.tags.get(res_id, {}).items():
                 if key == tag_key:
@@ -561,18 +527,18 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
 
         # EC2 AMI, resource type ec2:image
         for ami in self.ec2_backend.amis.values():
-            for value in get_ec2_values(ami.id):
+            for value in get_ec2_values(ami.id):  # type: ignore[assignment]
                 yield value
 
         # EC2 Instance, resource type ec2:instance
         for reservation in self.ec2_backend.reservations.values():
             for instance in reservation.instances:
-                for value in get_ec2_values(instance.id):
+                for value in get_ec2_values(instance.id):  # type: ignore[assignment]
                     yield value
 
         # EC2 NetworkInterface, resource type ec2:network-interface
         for eni in self.ec2_backend.enis.values():
-            for value in get_ec2_values(eni.id):
+            for value in get_ec2_values(eni.id):  # type: ignore[assignment]
                 yield value
 
         # TODO EC2 ReservedInstance
@@ -580,29 +546,29 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
         # EC2 SecurityGroup, resource type ec2:security-group
         for vpc in self.ec2_backend.groups.values():
             for sg in vpc.values():
-                for value in get_ec2_values(sg.id):
+                for value in get_ec2_values(sg.id):  # type: ignore[assignment]
                     yield value
 
         # EC2 Snapshot, resource type ec2:snapshot
         for snapshot in self.ec2_backend.snapshots.values():
-            for value in get_ec2_values(snapshot.id):
+            for value in get_ec2_values(snapshot.id):  # type: ignore[assignment]
                 yield value
 
         # TODO EC2 SpotInstanceRequest
 
         # EC2 Volume, resource type ec2:volume
         for volume in self.ec2_backend.volumes.values():
-            for value in get_ec2_values(volume.id):
+            for value in get_ec2_values(volume.id):  # type: ignore[assignment]
                 yield value
 
     def get_resources(
         self,
-        pagination_token=None,
-        resources_per_page=50,
-        tags_per_page=100,
-        tag_filters=None,
-        resource_type_filters=None,
-    ):
+        pagination_token: Optional[str] = None,
+        resources_per_page: int = 50,
+        tags_per_page: int = 100,
+        tag_filters: Optional[List[Dict[str, Any]]] = None,
+        resource_type_filters: Optional[List[str]] = None,
+    ) -> Tuple[Optional[str], List[Dict[str, Any]]]:
         # Simple range checking
         if 100 >= tags_per_page >= 500:
             raise RESTError(
@@ -666,7 +632,9 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
 
         return new_token, result
 
-    def get_tag_keys(self, pagination_token=None):
+    def get_tag_keys(
+        self, pagination_token: Optional[str] = None
+    ) -> Tuple[Optional[str], List[str]]:
 
         if pagination_token:
             if pagination_token not in self._pages:
@@ -712,7 +680,9 @@ class ResourceGroupsTaggingAPIBackend(BaseBackend):
 
         return new_token, result
 
-    def get_tag_values(self, pagination_token, key):
+    def get_tag_values(
+        self, pagination_token: Optional[str], key: str
+    ) -> Tuple[Optional[str], List[str]]:
 
         if pagination_token:
             if pagination_token not in self._pages:
diff --git a/moto/resourcegroupstaggingapi/responses.py b/moto/resourcegroupstaggingapi/responses.py
index 3ecea5f6e..190ae4337 100644
--- a/moto/resourcegroupstaggingapi/responses.py
+++ b/moto/resourcegroupstaggingapi/responses.py
@@ -1,22 +1,17 @@
 from moto.core.responses import BaseResponse
-from .models import resourcegroupstaggingapi_backends
+from .models import resourcegroupstaggingapi_backends, ResourceGroupsTaggingAPIBackend
 import json
 
 
 class ResourceGroupsTaggingAPIResponse(BaseResponse):
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__(service_name="resourcegroupstaggingapi")
 
     @property
-    def backend(self):
-        """
-        Backend
-        :returns: Resource tagging api backend
-        :rtype: moto.resourcegroupstaggingapi.models.ResourceGroupsTaggingAPIBackend
-        """
+    def backend(self) -> ResourceGroupsTaggingAPIBackend:
         return resourcegroupstaggingapi_backends[self.current_account][self.region]
 
-    def get_resources(self):
+    def get_resources(self) -> str:
         pagination_token = self._get_param("PaginationToken")
         tag_filters = self._get_param("TagFilters", [])
         resources_per_page = self._get_int_param("ResourcesPerPage", 50)
@@ -38,7 +33,7 @@ class ResourceGroupsTaggingAPIResponse(BaseResponse):
 
         return json.dumps(response)
 
-    def get_tag_keys(self):
+    def get_tag_keys(self) -> str:
         pagination_token = self._get_param("PaginationToken")
         pagination_token, tag_keys = self.backend.get_tag_keys(
             pagination_token=pagination_token
@@ -50,7 +45,7 @@ class ResourceGroupsTaggingAPIResponse(BaseResponse):
 
         return json.dumps(response)
 
-    def get_tag_values(self):
+    def get_tag_values(self) -> str:
         pagination_token = self._get_param("PaginationToken")
         key = self._get_param("Key")
         pagination_token, tag_values = self.backend.get_tag_values(
diff --git a/setup.cfg b/setup.cfg
index a973320f1..3eddd8bdd 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -239,7 +239,7 @@ disable = W,C,R,E
 enable = anomalous-backslash-in-string, arguments-renamed, dangerous-default-value, deprecated-module, function-redefined, import-self, redefined-builtin, redefined-outer-name, reimported, pointless-statement, super-with-arguments, unused-argument, unused-import, unused-variable, useless-else-on-loop, wildcard-import
 
 [mypy]
-files= moto/a*,moto/b*,moto/c*,moto/d*,moto/e*,moto/f*,moto/g*,moto/i*,moto/k*,moto/l*,moto/m*,moto/n*,moto/o*,moto/p*,moto/q*,moto/ram,moto/rds*,moto/redshift*,moto/rekognition,moto/scheduler
+files= moto/a*,moto/b*,moto/c*,moto/d*,moto/e*,moto/f*,moto/g*,moto/i*,moto/k*,moto/l*,moto/m*,moto/n*,moto/o*,moto/p*,moto/q*,moto/ram,moto/rds*,moto/redshift*,moto/rekognition,moto/resourcegroups*,moto/scheduler
 show_column_numbers=True
 show_error_codes = True
 disable_error_code=abstract