diff --git a/libs/cli/langgraph_cli/cli.py b/libs/cli/langgraph_cli/cli.py
index 960c7a545..0ee774159 100644
--- a/libs/cli/langgraph_cli/cli.py
+++ b/libs/cli/langgraph_cli/cli.py
@@ -767,7 +767,7 @@ def prepare_args_and_stdin(
     image: Optional[str] = None,
     # Like "langchain/langgraphjs-api" or "langchain/langgraph-api
     base_image: Optional[str] = None,
-):
+) -> tuple[list[str], str]:
     assert config_path.exists(), f"Config file not found: {config_path}"
     # prepare args
     stdin = langgraph_cli.docker.compose(
diff --git a/libs/cli/tests/unit_tests/cli/test_cli.py b/libs/cli/tests/unit_tests/cli/test_cli.py
index 33dbc7eeb..413a1f4bc 100644
--- a/libs/cli/tests/unit_tests/cli/test_cli.py
+++ b/libs/cli/tests/unit_tests/cli/test_cli.py
@@ -571,9 +571,9 @@ def test_build_generate_proper_build_context():
         build_context_pattern = re.compile(r"--build-context\s+(\w+)=([^\s]+)")
 
         build_contexts = re.findall(build_context_pattern, result.output)
-        assert (
-            len(build_contexts) == 2
-        ), f"Expected 2 build contexts, but found {len(build_contexts)}"
+        assert len(build_contexts) == 2, (
+            f"Expected 2 build contexts, but found {len(build_contexts)}"
+        )
 
 
 def test_dockerfile_command_with_api_version() -> None: