Worked on the google/adk-python repository to modernize type handling in Python by implementing support for PEP 604 union syntax in function parameter parsing. Addressed a critical issue where schema properties were lost during union collapsing, ensuring that nested attributes such as items and properties are preserved for accurate JSON schema generation. Enhanced the unit test suite to validate complex type fallback paths, specifically updating tests to exercise tuple-based fallbacks. Leveraged Python, type annotations, and unit testing to improve type safety and compatibility with modern typing standards, ultimately reducing downstream client bugs and maintenance overhead while stabilizing parameter parsing logic.