diff --git a/src/google/adk/cli/utils/agent_loader.py b/src/google/adk/cli/utils/agent_loader.py
index 5df524f8..f8c05a8d 100644
--- a/src/google/adk/cli/utils/agent_loader.py
+++ b/src/google/adk/cli/utils/agent_loader.py
@@ -455,6 +455,17 @@ class AgentLoader(BaseAgentLoader):
     self._agent_cache[agent_name] = agent_or_app
     return agent_or_app
 
+  @staticmethod
+  def _looks_like_agent_dir(dir_path: Path) -> bool:
+    """Returns True if the directory holds a loadable agent definition."""
+    try:
+      return (
+          is_single_agent_directory(dir_path)
+          or (dir_path / "__init__.py").is_file()
+      )
+    except Exception:
+      return False
+
   @override
   def list_agents(self) -> list[str]:
     """Lists all agents available in the agent loader (sorted alphabetically)."""
@@ -467,6 +478,7 @@ class AgentLoader(BaseAgentLoader):
         if os.path.isdir(os.path.join(base_path, x))
         and not x.startswith(".")
         and x != "__pycache__"
+        and self._looks_like_agent_dir(base_path / x)
     ]
     agent_names.sort()
     return agent_names
diff --git a/tests/unittests/cli/utils/test_agent_loader.py b/tests/unittests/cli/utils/test_agent_loader.py
index 65ae7cd6..ef4909d5 100644
--- a/tests/unittests/cli/utils/test_agent_loader.py
+++ b/tests/unittests/cli/utils/test_agent_loader.py
@@ -287,6 +287,48 @@ class TestAgentLoader:
       assert agent2 is not agent3
       assert agent1.agent_id != agent2.agent_id != agent3.agent_id
 
+  def test_list_agents_skips_directories_without_a_loadable_agent(self):
+    """Stray non-agent directories under agents_dir must not be listed."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+      temp_path = Path(temp_dir)
+
+      self.create_agent_structure(
+          temp_path, "real_agent", "package_with_agent_module"
+      )
+      # A stray directory with no agent.py or root_agent.yaml,
+      # e.g. one created as a side effect of local storage keyed by an
+      # unmapped app name.
+      (temp_path / "stray_dir").mkdir()
+
+      loader = AgentLoader(str(temp_path))
+
+      assert loader.list_agents() == ["real_agent"]
+
+  def test_list_agents_handles_permission_error(self):
+    """Permission errors on subdirectories must be handled gracefully."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+      temp_path = Path(temp_dir)
+      self.create_agent_structure(
+          temp_path, "real_agent", "package_with_agent_module"
+      )
+
+      # Create a directory that we will simulate permission error on
+      no_perm_dir = temp_path / "no_perm_dir"
+      no_perm_dir.mkdir()
+
+      # We want to mock is_file for paths under no_perm_dir to raise PermissionError
+      original_is_file = Path.is_file
+
+      def mock_is_file(self_path):
+        if no_perm_dir in self_path.parents or self_path == no_perm_dir:
+          raise PermissionError("[Errno 13] Permission denied")
+        return original_is_file(self_path)
+
+      loader = AgentLoader(str(temp_path))
+
+      with mock.patch.object(Path, "is_file", mock_is_file):
+        assert loader.list_agents() == ["real_agent"]
+
   def test_error_messages_use_os_sep_consistently(self):
     """Verify error messages use os.sep instead of hardcoded '/'."""
     del self