test: cover Morph tool param gating in unit test shard

tests/llm_translation is outside the coverage-reporting unit shards, so
add registry-gating tests under tests/test_litellm/llms/morph.

Claude-Session: https://claude.ai/code/session_01LDxX4kpF7ajmSNbhzPsqNT

tests/test_litellm/llms/morph/chat/test_morph_chat_transformation.py

@@ -0,0 +1,76 @@
+import pytest
+
+import litellm
+from litellm.exceptions import UnsupportedParamsError
+from litellm.llms.morph.chat.transformation import MorphChatConfig
+
+NO_TOOLS_MODEL = "morph-v3-large"
+TOOL_CALLING_MODEL = "morph-glm53flash"
+UNMAPPED_MODEL = "morph-unreleased-model"
+TOOLS = [
+    {
+        "type": "function",
+        "function": {"name": "noop", "parameters": {"type": "object", "properties": {}}},
+    }
+]
+
+
+@pytest.fixture(autouse=True)
+def local_model_cost_map(monkeypatch):
+    monkeypatch.setenv("LITELLM_LOCAL_MODEL_COST_MAP", "True")
+    monkeypatch.setattr(litellm, "model_cost", litellm.get_model_cost_map(url=""))
+
+
+@pytest.mark.parametrize("model", [NO_TOOLS_MODEL, f"morph/{NO_TOOLS_MODEL}", "morph-v3-fast"])
+def test_tool_params_are_withheld_when_registry_disables_function_calling(model):
+    supported_params = MorphChatConfig().get_supported_openai_params(model)
+
+    assert "tools" not in supported_params
+    assert "tool_choice" not in supported_params
+    assert "response_format" in supported_params
+    assert "temperature" in supported_params
+
+
+@pytest.mark.parametrize("model", [TOOL_CALLING_MODEL, f"morph/{TOOL_CALLING_MODEL}", UNMAPPED_MODEL])
+def test_tool_params_pass_through_unless_registry_disables_function_calling(model):
+    supported_params = MorphChatConfig().get_supported_openai_params(model)
+
+    assert "tools" in supported_params
+    assert "tool_choice" in supported_params
+
+
+def test_tools_for_model_without_function_calling_raise_unsupported_params():
+    with pytest.raises(UnsupportedParamsError):
+        litellm.get_optional_params(
+            model=NO_TOOLS_MODEL,
+            custom_llm_provider="morph",
+            tools=TOOLS,
+            drop_params=False,
+        )
+
+
+def test_tools_for_model_without_function_calling_are_dropped_with_drop_params():
+    optional_params = litellm.get_optional_params(
+        model=NO_TOOLS_MODEL,
+        custom_llm_provider="morph",
+        tools=TOOLS,
+        tool_choice="auto",
+        temperature=0.2,
+        drop_params=True,
+    )
+
+    assert "tools" not in optional_params
+    assert "tool_choice" not in optional_params
+    assert optional_params["temperature"] == 0.2
+
+
+def test_tools_for_tool_calling_model_are_forwarded():
+    optional_params = litellm.get_optional_params(
+        model=TOOL_CALLING_MODEL,
+        custom_llm_provider="morph",
+        tools=TOOLS,
+        tool_choice="required",
+    )
+
+    assert optional_params["tools"] == TOOLS
+    assert optional_params["tool_choice"] == "required"