diff --git a/src/google/adk/cli/cli_deploy.py b/src/google/adk/cli/cli_deploy.py
index 2772cf1d3b..d498603a28 100644
--- a/src/google/adk/cli/cli_deploy.py
+++ b/src/google/adk/cli/cli_deploy.py
@@ -601,6 +601,36 @@ def _validate_gcloud_extra_args(
       )
 
 
+def _validate_agent_folder_name(agent_folder: str) -> str:
+  """Validates that the agent directory name is a valid Python identifier.
+
+  Agent Engine requires the agent folder to be importable as a Python module.
+  Directory names containing hyphens (-) or other non-identifier characters
+  lead to syntax and import errors at deployment runtime.
+
+  Args:
+    agent_folder: Path to the agent directory.
+
+  Returns:
+    The validated folder name.
+
+  Raises:
+    click.ClickException: If the folder name is not a valid Python identifier.
+  """
+  folder_name = os.path.basename(os.path.normpath(agent_folder))
+  if not folder_name.isidentifier():
+    suggested = re.sub(r'\W|^(?=\d)', '_', folder_name)
+    if not suggested.isidentifier():
+      suggested = f'_{suggested}'
+    raise click.ClickException(
+        f"Agent directory name '{folder_name}' is not a valid Python"
+        " identifier (cannot contain dashes '-' or special characters)."
+        " Agent Engine requires the directory name to be a valid Python"
+        f" module name. Please rename your agent folder (e.g., '{suggested}')."
+    )
+  return folder_name
+
+
 def _validate_agent_import(
     agent_src_path: str,
     adk_app_object: str,
@@ -1107,7 +1137,7 @@ def to_agent_engine(
       Overrides `worker_pool` / `build_config.worker_pool` from
       `.agent_engine_config.json` when both are present.
   """
-  app_name = os.path.basename(os.path.normpath(agent_folder))
+  app_name = _validate_agent_folder_name(agent_folder)
   _validate_app_name(app_name)
   display_name = display_name or app_name
   parent_folder = os.path.dirname(os.path.normpath(agent_folder))
diff --git a/tests/unittests/cli/utils/test_cli_deploy.py b/tests/unittests/cli/utils/test_cli_deploy.py
index eea406f018..918593d65f 100644
--- a/tests/unittests/cli/utils/test_cli_deploy.py
+++ b/tests/unittests/cli/utils/test_cli_deploy.py
@@ -1483,7 +1483,6 @@ def test_removes_directory_tree(self, tmp_path: Path) -> None:
 
   def test_removes_readonly_files(self, tmp_path: Path) -> None:
     """It should remove a tree containing read-only files."""
-    import os
     import stat
 
     d = tmp_path / "ro_dir"
@@ -1509,6 +1508,57 @@ def test_on_rm_error_clears_readonly_and_retries(
     assert not ro_file.exists()
 
 
+# _validate_agent_folder_name tests
+
+
+class TestValidateAgentFolderName:
+  """Tests for the _validate_agent_folder_name helper."""
+
+  def test_valid_identifier_succeeds(self) -> None:
+    """A valid identifier folder name should succeed and return basename."""
+    assert (
+        cli_deploy._validate_agent_folder_name("/path/to/my_agent")
+        == "my_agent"
+    )
+    assert cli_deploy._validate_agent_folder_name("agent123") == "agent123"
+    assert (
+        cli_deploy._validate_agent_folder_name("/path/to/my_agent/")
+        == "my_agent"
+    )
+
+  def test_invalid_folder_name_with_dashes_raises(self) -> None:
+    """A folder name with dashes should raise ClickException with suggestions."""
+    with pytest.raises(click.ClickException) as exc_info:
+      cli_deploy._validate_agent_folder_name("my-agent-app")
+    assert "not a valid Python identifier" in str(exc_info.value)
+    assert "my_agent_app" in str(exc_info.value)
+
+  def test_invalid_folder_name_starting_with_number_raises(self) -> None:
+    """A folder name starting with a number should raise ClickException."""
+    with pytest.raises(click.ClickException) as exc_info:
+      cli_deploy._validate_agent_folder_name("123agent")
+    assert "not a valid Python identifier" in str(exc_info.value)
+    assert "_123agent" in str(exc_info.value)
+
+  def test_to_agent_engine_raises_on_dashed_folder_name(
+      self, tmp_path: Path
+  ) -> None:
+    """to_agent_engine should fail early when agent directory contains dashes."""
+    dashed_agent = tmp_path / "dashed-agent-name"
+    dashed_agent.mkdir()
+    (dashed_agent / "agent.py").write_text("root_agent = 'test'\n")
+    (dashed_agent / "__init__.py").touch()
+
+    with pytest.raises(click.ClickException) as exc_info:
+      cli_deploy.to_agent_engine(
+          agent_folder=str(dashed_agent),
+          project="test-project",
+          region="us-central1",
+      )
+    assert "not a valid Python identifier" in str(exc_info.value)
+    assert "dashed_agent_name" in str(exc_info.value)
+
+
 _VALID_WORKER_POOL = (
     "projects/my-gcp-project/locations/us-central1/workerPools/my-private-pool"
 )