diff --git a/litellm/llms/ollama/chat/transformation.py b/litellm/llms/ollama/chat/transformation.py
index d6aa1f1743b..2fdf58ac1ec 100644
--- a/litellm/llms/ollama/chat/transformation.py
+++ b/litellm/llms/ollama/chat/transformation.py
@@ -234,13 +234,16 @@ class OllamaChatConfig(BaseConfig):
         litellm_params: dict,
         headers: dict,
     ) -> dict:
-        stream: Final = optional_params.pop("stream", False)
-        format: Final = optional_params.pop("format", None)
-        keep_alive: Final = optional_params.pop("keep_alive", None)
-        think: Final = optional_params.pop("think", None)
-        function_name: Final = optional_params.pop("function_name", None)
+        request_params: Final = (
+            optional_params.copy()
+        )  # mutable-ok: request-local copy protects caller-owned logging data
+        stream: Final = request_params.pop("stream", False)
+        format: Final = request_params.pop("format", None)
+        keep_alive: Final = request_params.pop("keep_alive", None)
+        think: Final = request_params.pop("think", None)
+        function_name: Final = request_params.pop("function_name", None)
         litellm_params["function_name"] = function_name
-        tools: Final = optional_params.pop("tools", None)
+        tools: Final = request_params.pop("tools", None)
 
         new_messages: Final = []
         for m in messages:
@@ -289,13 +292,13 @@ class OllamaChatConfig(BaseConfig):
         # Load Config
         config: Final = self.get_config()
         for k, v in config.items():
-            if k not in optional_params:
-                optional_params[k] = v
+            if k not in request_params:
+                request_params[k] = v
 
         data: Final = {
             "model": model,
             "messages": new_messages,
-            "options": optional_params,
+            "options": request_params,
             "stream": stream,
         }
         if format is not None:
diff --git a/tests/test_litellm/llms/ollama/test_ollama_chat_transformation.py b/tests/test_litellm/llms/ollama/test_ollama_chat_transformation.py
index 8f3dbf7b0d9..ccb4f6fd1e2 100644
--- a/tests/test_litellm/llms/ollama/test_ollama_chat_transformation.py
+++ b/tests/test_litellm/llms/ollama/test_ollama_chat_transformation.py
@@ -812,6 +812,38 @@ class TestOllamaReasoningContentStreaming:
 
 
 class TestOllamaToolCallTransformation:
+    def test_transform_request_preserves_logged_tool_schema(self):
+        config = OllamaChatConfig()
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "get_weather",
+                    "description": "Get weather for a location",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {"location": {"type": "string"}},
+                        "required": ["location"],
+                    },
+                },
+            }
+        ]
+        optional_params = {"tools": tools, "stream": False, "num_ctx": 262144}
+
+        result = config.transform_request(
+            model="gemma4:27b",
+            messages=cast(
+                list[AllMessageValues],
+                [{"role": "user", "content": "Weather in London?"}],
+            ),
+            optional_params=optional_params,
+            litellm_params={},
+            headers={},
+        )
+
+        assert result["tools"] == tools
+        assert optional_params == {"tools": tools, "stream": False, "num_ctx": 262144}
+
     def test_transform_request_preserves_tool_calls(self):
         """
         tool_calls on assistant messages must survive transform_request.