fix(anthropic): handle tool_choice type 'none' in messages API

litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py

@@ -782,6 +782,8 @@ def translate_anthropic_tool_choice_to_openai(
             return ChatCompletionToolChoiceObjectParam(
                 type="function", function=tc_function_param
             )
+        elif tool_choice["type"] == "none":
+            return "none"
         else:
             raise ValueError(
                 "Incompatible tool choice param submitted - {}".format(tool_choice)

tests/test_litellm/llms/anthropic/experimental_pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py

@@ -2162,16 +2162,19 @@ def test_incomplete_required_gets_completed(self):
         assert sorted(schema["required"]) == ["age", "email", "name"]
 
     def test_invalid_output_format_returns_none(self):
-        assert (
-            self.adapter.translate_anthropic_output_format_to_openai("invalid") is None
-        )
-        assert (
-            self.adapter.translate_anthropic_output_format_to_openai({"type": "text"})
-            is None
-        )
-        assert (
-            self.adapter.translate_anthropic_output_format_to_openai(
-                {"type": "json_schema"}
-            )
-            is None
-        )
+        assert self.adapter.translate_anthropic_output_format_to_openai("invalid") is None
+        assert self.adapter.translate_anthropic_output_format_to_openai({"type": "text"}) is None
+        assert self.adapter.translate_anthropic_output_format_to_openai({"type": "json_schema"}) is None
+
+
+def test_translate_anthropic_tool_choice_none():
+    """
+    Regression test for issue #24443.
+
+    tool_choice={"type": "none"} should be translated to "none" for OpenAI format,
+    not raise a ValueError.
+    """
+    adapter = LiteLLMAnthropicMessagesAdapter()
+
+    result = adapter.translate_anthropic_tool_choice_to_openai({"type": "none"})
+    assert result == "none"