fix(openai-agents): serialize complex output types to JSON for AttributeValue compatibility

Handle edge cases where FunctionCallOutput and ResponseCustomToolCallOutputParam contain complex output types (lists, dicts) that don't match AttributeValue type. Serialize these to JSON strings while preserving None and string values.

Author: codefromthecrypt

python/instrumentation/openinference-instrumentation-openai-agents/src/openinference/instrumentation/openai_agents/_processor.py

@@ -349,8 +349,14 @@ def _get_attributes_from_response_custom_tool_call_output_param(
     yield f"{prefix}{MessageAttributes.MESSAGE_ROLE}", "tool"
     if (call_id := obj.get("call_id")) is not None:
         yield f"{prefix}{MessageAttributes.MESSAGE_TOOL_CALL_ID}", call_id
-    if (output := obj.get("output")) is not None:
-        yield f"{prefix}{MessageAttributes.MESSAGE_CONTENT}", output
+    if "output" in obj:
+        output = obj["output"]
+        # Serialize complex output types to JSON string, but preserve None
+        if output is None or isinstance(output, str):
+            output_value = output
+        else:
+            output_value = safe_json_dumps(output)
+        yield f"{prefix}{MessageAttributes.MESSAGE_CONTENT}", output_value
 
 
 def _get_attributes_from_function_call_output(
@@ -359,7 +365,13 @@ def _get_attributes_from_function_call_output(
 ) -> Iterator[tuple[str, AttributeValue]]:
     yield f"{prefix}{MESSAGE_ROLE}", "tool"
     yield f"{prefix}{MESSAGE_TOOL_CALL_ID}", obj["call_id"]
-    yield f"{prefix}{MESSAGE_CONTENT}", obj["output"]
+    # Serialize complex output types to JSON string, but preserve None
+    output = obj["output"]
+    if output is None or isinstance(output, str):
+        output_value = output
+    else:
+        output_value = safe_json_dumps(output)
+    yield f"{prefix}{MESSAGE_CONTENT}", output_value
 
 
 def _get_attributes_from_generation_span_data(

python/instrumentation/openinference-instrumentation-openai-agents/tests/test_span_attribute_helpers.py

@@ -38,6 +38,9 @@
     ResponseUsage,
     Tool,
 )
+from openai.types.responses.response_custom_tool_call_output_param import (
+    ResponseCustomToolCallOutputParam,
+)
 from openai.types.responses.response_function_web_search_param import ActionSearch
 from openai.types.responses.response_input_item_param import (
     ComputerCallOutput,
@@ -265,6 +268,53 @@
             },
             id="item_reference",
         ),
+        pytest.param(
+            [
+                ResponseCustomToolCallOutputParam(
+                    type="custom_tool_call_output",
+                    call_id="custom-123",
+                    output="simple result",
+                )
+            ],
+            {
+                "llm.input_messages.1.message.content": "simple result",
+                "llm.input_messages.1.message.role": "tool",
+                "llm.input_messages.1.message.tool_call_id": "custom-123",
+            },
+            id="custom_tool_call_output_string",
+        ),
+        pytest.param(
+            [
+                ResponseCustomToolCallOutputParam(
+                    type="custom_tool_call_output",
+                    call_id="custom-123",
+                    output=[{"type": "text", "text": "complex result"}],  # type: ignore[typeddict-item]
+                )
+            ],
+            {
+                "llm.input_messages.1.message.content": (
+                    '[{"type": "text", "text": "complex result"}]'
+                ),
+                "llm.input_messages.1.message.role": "tool",
+                "llm.input_messages.1.message.tool_call_id": "custom-123",
+            },
+            id="custom_tool_call_output_list",
+        ),
+        pytest.param(
+            [
+                ResponseCustomToolCallOutputParam(
+                    type="custom_tool_call_output",
+                    call_id="custom-123",
+                    output={"status": "success", "data": 42},  # type: ignore[dict-item]
+                )
+            ],
+            {
+                "llm.input_messages.1.message.content": '{"status": "success", "data": 42}',
+                "llm.input_messages.1.message.role": "tool",
+                "llm.input_messages.1.message.tool_call_id": "custom-123",
+            },
+            id="custom_tool_call_output_dict",
+        ),
     ],
 )
 def test_get_attributes_from_input(
@@ -427,6 +477,30 @@ def test_get_attributes_from_response_function_tool_call_param(
             },
             id="none_output",
         ),
+        pytest.param(
+            {
+                "call_id": "123",
+                "output": [{"type": "text", "text": "result"}],
+            },
+            {
+                "message.content": '[{"type": "text", "text": "result"}]',
+                "message.role": "tool",
+                "message.tool_call_id": "123",
+            },
+            id="list_output",
+        ),
+        pytest.param(
+            {
+                "call_id": "123",
+                "output": {"result": "success", "value": 42},
+            },
+            {
+                "message.content": '{"result": "success", "value": 42}',
+                "message.role": "tool",
+                "message.tool_call_id": "123",
+            },
+            id="dict_output",
+        ),
     ],
 )
 def test_get_attributes_from_function_call_output(