diff --git a/src/google/adk/optimization/local_eval_sampler.py b/src/google/adk/optimization/local_eval_sampler.py
index 817ce0ca618..9044173d86a 100644
--- a/src/google/adk/optimization/local_eval_sampler.py
+++ b/src/google/adk/optimization/local_eval_sampler.py
@@ -164,13 +164,14 @@ def __init__(
     self._train_eval_set = self._config.train_eval_set
     self._train_eval_case_ids = (
         self._config.train_eval_case_ids
-        or self._get_eval_case_ids(self._train_eval_set)
+        if self._config.train_eval_case_ids is not None
+        else self._get_eval_case_ids(self._train_eval_set)
     )
 
     self._validation_eval_set = (
         self._config.validation_eval_set or self._train_eval_set
     )
-    if self._config.validation_eval_case_ids:
+    if self._config.validation_eval_case_ids is not None:
       self._validation_eval_case_ids = self._config.validation_eval_case_ids
     elif self._config.validation_eval_set:
       self._validation_eval_case_ids = self._get_eval_case_ids(
diff --git a/tests/unittests/optimization/local_eval_sampler_test.py b/tests/unittests/optimization/local_eval_sampler_test.py
index 546b632bba0..5438966e28a 100644
--- a/tests/unittests/optimization/local_eval_sampler_test.py
+++ b/tests/unittests/optimization/local_eval_sampler_test.py
@@ -197,6 +197,23 @@ def test_extract_single_invocation_info():
                 "_validation_eval_case_ids": ["v1"],
             },
         ),
+        (
+            {"train_eval_set": "train_set", "train_eval_case_ids": []},
+            {
+                "_train_eval_case_ids": [],
+                "_validation_eval_case_ids": [],
+            },
+        ),
+        (
+            {
+                "train_eval_set": "train_set",
+                "validation_eval_case_ids": [],
+            },
+            {
+                "_train_eval_case_ids": ["train_set_1", "train_set_2"],
+                "_validation_eval_case_ids": [],
+            },
+        ),
     ],
 )
 def test_local_eval_service_interface_init(