diff --git a/tuner/tuner/candidate_gen.py b/tuner/tuner/candidate_gen.py
index 1c6ef5c8d..2a544ef55 100644
--- a/tuner/tuner/candidate_gen.py
+++ b/tuner/tuner/candidate_gen.py
@@ -61,8 +61,8 @@ def apply_configuration(
     expr5 = re.compile(r"\"amdgpu-waves-per-eu\" = \"([0-9])\"")
     repl0 = f"<intrinsic = {intrinsic}, subgroup_m_count = {subgroup_m_count}, subgroup_n_count = {subgroup_n_count}>"
     repl1 = f'LLVMGPUVectorDistribute workgroup_size = [{", ".join(map(str, configuration.workgroup_size))}] subgroup_size = {configuration.subgroup_size},'
-    repl2 = f'workgroup = [{", ".join(map(str, workgroup_sizes))}]'
-    repl3 = f'reduction = [{", ".join(map(str, reduction_sizes))}]'
+    repl2 = f"workgroup = {workgroup_sizes}"
+    repl3 = f"reduction = {reduction_sizes}"
     repl4 = f"gpu_pipeline_options = {configuration.gpu_pipeline_options}"
     repl5 = f'"amdgpu-waves-per-eu" = "{configuration.waves_per_eu}"'
 
diff --git a/tuner/tuner/common.py b/tuner/tuner/common.py
index a839ad4c4..702008f5e 100644
--- a/tuner/tuner/common.py
+++ b/tuner/tuner/common.py
@@ -125,14 +125,14 @@ def get_intrinsic(config: Configuration) -> Optional[iree_gpu.MMAAttr]:
     return None
 
 
-def get_tilesize_workgroup(config: Configuration) -> list[int]:
+def get_workgroup_tile_sizes(config: Configuration) -> list[int]:
     if "workgroup" in config.lowering_config.attributes:
         workgroup_attrs = config.lowering_config.attributes["workgroup"]
         return [attr.value for attr in workgroup_attrs]
     return []
 
 
-def get_tilesize_reduction(config: Configuration) -> list[int]:
+def get_reduction_tile_sizes(config: Configuration) -> list[int]:
     if "reduction" in config.lowering_config.attributes:
         reduction_attrs = config.lowering_config.attributes["reduction"]
         return [attr.value for attr in reduction_attrs]
@@ -163,26 +163,29 @@ def get_lowering_config(
         promoted_value = value
         match key:
             case "workgroup" | "reduction":
-                assert isinstance(
-                    value, (list, ir.ArrayAttr)
-                ), f"Unsupported type for key '{key}': {type(value).__name__}"
                 if isinstance(value, list):
                     promoted_value = ir.ArrayAttr.get(
                         [tuner_ctx.type.getI64(x) for x in value]
                     )
+                elif not isinstance(value, ir.ArrayAttr):
+                    assert (
+                        False
+                    ), f"Unsupported type for key '{key}': {type(value).__name__}"
             case "subgroup_m_count" | "subgroup_n_count":
-                assert isinstance(
-                    value, (int, tuner_ctx.type.i64)
-                ), f"Unsupported type for key '{key}': {type(value).__name__}"
                 if isinstance(value, int):
                     promoted_value = tuner_ctx.type.getI64(value)
+                elif not isinstance(value, tuner_ctx.type.i64):
+                    assert (
+                        False
+                    ), f"Unsupported type for key '{key}': {type(value).__name__}"
             case "mma_kind":
-                assert isinstance(
-                    value, iree_gpu.MMAAttr
-                ), f"Unsupported type for key '{key}': {type(value).__name__}"
+                if not isinstance(value, iree_gpu.MMAAttr):
+                    assert (
+                        False
+                    ), f"Unsupported type for key '{key}': {type(value).__name__}"
             case _:
-                raise KeyError(f"Unhandled key in lowering configuration: {key}")
-        # Single assignment after the match.
+                assert False, f"Unhandled key in lowering configuration: {key}"
+
         lowering_config_dict[key] = promoted_value
     lowering_config_attrs = ir.DictAttr.get(lowering_config_dict)
     return iree_gpu.LoweringConfigAttr.get(lowering_config_attrs)
diff --git a/tuner/tuner/dispatch_parser.py b/tuner/tuner/dispatch_parser.py
index 503ece345..ad63ba815 100644
--- a/tuner/tuner/dispatch_parser.py
+++ b/tuner/tuner/dispatch_parser.py
@@ -21,17 +21,17 @@ def parse_tensor_type(tensor_type: str) -> ShapedType:
 
 
 def get_mmt_workgroup_sizes(configuration: Configuration):
-    return get_tilesize_workgroup(configuration)
+    return get_workgroup_tile_sizes(configuration)
 
 
 def get_mmt_reduction_sizes(configuration: Configuration):
-    return get_tilesize_reduction(configuration)
+    return get_reduction_tile_sizes(configuration)
 
 
 def get_contract_workgroup_sizes(
     configuration: Configuration, tile_dims: str
 ) -> list[int]:
-    m, n, _k = get_tilesize_workgroup(configuration)
+    m, n, _k = get_workgroup_tile_sizes(configuration)
 
     workgroup_size = [1] * len(tile_dims)
     for idx, dim in enumerate(tile_dims):
@@ -48,7 +48,7 @@ def get_contract_workgroup_sizes(
 def get_contract_reduction_sizes(
     configuration: Configuration, tile_dims: str
 ) -> list[int]:
-    _m, _n, k = get_tilesize_reduction(configuration)
+    _m, _n, k = get_reduction_tile_sizes(configuration)
     reduction_size = [0] * len(tile_dims)
     for idx, dim in enumerate(tile_dims):
         if dim == "k":
@@ -58,11 +58,11 @@ def get_contract_reduction_sizes(
 
 
 def get_batch_mmt_workgroup_sizes(configuration: Configuration) -> list[int]:
-    return [1] + get_tilesize_workgroup(configuration)
+    return [1] + get_workgroup_tile_sizes(configuration)
 
 
 def get_batch_mmt_reduction_sizes(configuration: Configuration) -> list[int]:
-    return [0] + get_tilesize_reduction(configuration)
+    return [0] + get_reduction_tile_sizes(configuration)
 
 
 class MlirRegex(Enum):
@@ -171,12 +171,12 @@ def get_conv_workgroup_sizes(self, configuration: Configuration) -> list[int]:
 
         oh = 1
 
-        ow, oc, _ic = get_tilesize_workgroup(configuration)
+        ow, oc, _ic = get_workgroup_tile_sizes(configuration)
 
         return [batch, oh, ow, oc, fh, fw, 0]
 
     def get_conv_reduction_sizes(self, configuration: Configuration) -> list[int]:
-        _ow, _oc, ic = get_tilesize_reduction(configuration)
+        _ow, _oc, ic = get_reduction_tile_sizes(configuration)
 
         return [0, 0, 0, 0, 0, 0, ic]