The function _set_span_data_attribute is defined twice in this file - once at lines 505-511 and again at lines 514-520. In Python, the second definition silently overrides the first. While both definitions appear identical in this case, duplicate function definitions are a code smell and indicate a copy-paste error during the PR. This will work at runtime but creates maintenance confusion and suggests unintended code duplication.

The span streaming path asserts span["status"] == "error" and checks SPANDATA.MCP_TOOL_RESULT_IS_ERROR not in span["attributes"] (lines 917-918), but the non-streaming path (lines 919-936) only verifies the error event payload without asserting on the span's error status. This asymmetry means the non-streaming path has less test coverage for verifying that errors properly propagate to the span status.