fix(responses): normalize empty function tool parameters to valid JSON Schema

src/ogx/providers/inline/responses/builtin/responses/streaming.py

@@ -1580,8 +1580,13 @@ def make_openai_tool(tool_name: str, tool: ToolDef) -> ChatCompletionToolParam:
 
         for input_tool in tools:
             if input_tool.type == "function":
+                func = input_tool.model_dump(exclude_none=True)
+                if not func.get("parameters"):
+                    func["parameters"] = {"type": "object"}
+                elif "type" not in func["parameters"]:
+                    func["parameters"]["type"] = "object"
                 self.ctx.chat_tools.append(
-                    ChatCompletionToolParam(type="function", function=input_tool.model_dump(exclude_none=True))  # type: ignore[typeddict-item,arg-type]  # Dict compatible with FunctionDefinition
+                    ChatCompletionToolParam(type="function", function=func)  # type: ignore[typeddict-item,arg-type]  # Dict compatible with FunctionDefinition
                 )
             elif input_tool.type in WebSearchToolTypes:
                 tool_name = "web_search"

tests/unit/providers/responses/builtin/test_openai_responses_tools.py

@@ -6,6 +6,8 @@
 
 from unittest.mock import patch
 
+import pytest
+
 from openai.types.chat.chat_completion_chunk import (
     ChatCompletionChunk,
     Choice,
@@ -844,6 +846,39 @@ async def fake_stream_no_args():
     assert parsed == {}
 
 
+@pytest.mark.parametrize(
+    "input_params,expected_params",
+    [
+        ({}, {"type": "object"}),
+        ({"properties": {"x": {"type": "string"}}}, {"type": "object", "properties": {"x": {"type": "string"}}}),
+        ({"type": "object", "properties": {}}, {"type": "object", "properties": {}}),
+    ],
+    ids=["empty", "missing-type", "already-valid"],
+)
+async def test_function_tool_empty_parameters_normalized(
+    openai_responses_impl, mock_inference_api, input_params, expected_params
+):
+    """Test that empty or type-less function parameters are normalized to valid JSON Schema."""
+    model = "meta-llama/Llama-3.1-8B-Instruct"
+    mock_inference_api.openai_chat_completion.return_value = fake_stream()
+
+    await openai_responses_impl.create_openai_response(
+        input="test",
+        model=model,
+        stream=False,
+        tools=[
+            OpenAIResponseInputToolFunction(
+                name="my_func",
+                description="A function",
+                parameters=input_params,
+            )
+        ],
+    )
+
+    params = mock_inference_api.openai_chat_completion.call_args[0][0]
+    assert params.tools[0]["function"]["parameters"] == expected_params
+
+
 async def test_function_tool_strict_field_excluded_when_none(openai_responses_impl, mock_inference_api):
     """Test that function tool 'strict' field is excluded when None (fix for #4617)."""
     input_text = "What is the weather?"