Python: Enhance tool call handling and function result processing (#790)

* Tool call enhancement

* add tests

* fix comments

* resolve comments

---------

Co-authored-by: Chris <66376200+crickman@users.noreply.github.com>
Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>

python/packages/main/agent_framework/openai/_chat_client.py

@@ -185,10 +185,10 @@ class OpenAIBaseChatClient(OpenAIBase, BaseChatClient):
             if choice.finish_reason:
                 finish_reason = FinishReason(value=choice.finish_reason)
             contents: list[Contents] = []
-            if parsed_tool_calls := [tool for tool in self._get_tool_calls_from_chat_choice(choice)]:
-                contents.extend(parsed_tool_calls)
             if text_content := self._parse_text_from_choice(choice):
                 contents.append(text_content)
+            if parsed_tool_calls := [tool for tool in self._get_tool_calls_from_chat_choice(choice)]:
+                contents.extend(parsed_tool_calls)
             messages.append(ChatMessage(role="assistant", contents=contents))
         return ChatResponse(
             response_id=response.id,
@@ -354,8 +354,13 @@ class OpenAIBaseChatClient(OpenAIBase, BaseChatClient):
                         args["tool_calls"] = [self._openai_content_parser(content)]  # type: ignore
                 case FunctionResultContent():
                     args["tool_call_id"] = content.call_id
-                    if content.result:
+                    if content.result is not None:
                         args["content"] = prepare_function_call_results(content.result)
+                    elif content.exception is not None:
+                        # Send the exception message to the model
+                        # Otherwise we won't have any channels to talk to OpenAI
+                        # TODO(yuge): This should ideally be customizable
+                        args["content"] = "Error: " + str(content.exception)
                 case _:
                     if "content" not in args:
                         args["content"] = []

python/packages/main/agent_framework/openai/_shared.py

@@ -50,21 +50,28 @@ __all__ = [
 ]
 
 
+def _prepare_function_call_results_as_dumpable(content: Contents | Any | list[Contents | Any]) -> Any:
+    if isinstance(content, list):
+        # Particularly deal with lists of BaseModel
+        return [_prepare_function_call_results_as_dumpable(item) for item in content]
+    if isinstance(content, dict):
+        return {k: _prepare_function_call_results_as_dumpable(v) for k, v in content.items()}
+    if isinstance(content, BaseModel):
+        return content.model_dump(exclude={"raw_representation", "additional_properties"})
+    return content
+
+
 def prepare_function_call_results(content: Contents | Any | list[Contents | Any]) -> str | list[str]:
     """Prepare the values of the function call results."""
-    if isinstance(content, list):
-        results: list[str] = []
-        for item in content:
-            res = prepare_function_call_results(item)
-            if isinstance(res, list):
-                results.extend(res)
-            else:
-                results.append(res)
-        return results[0] if len(results) == 1 else json.dumps(results)
     if isinstance(content, BaseModel):
-        return content.model_dump_json(exclude_none=True, exclude={"raw_representation", "additional_properties"})
+        # BaseModel is already dumpable, shortcut for performance
+        return content.model_dump_json(exclude={"raw_representation", "additional_properties"})
+
+    dumpable = _prepare_function_call_results_as_dumpable(content)
+    if isinstance(dumpable, str):
+        return dumpable
     # fallback
-    return json.dumps(content)
+    return json.dumps(dumpable)
 
 
 class OpenAISettings(AFBaseSettings):