Luka Pecnik enhanced the BerriAI/litellm repository by delivering an input schema update for Anthropic tools that preserves the $defs property, addressing potential reference drift during cross-model integrations. Using Python and leveraging skills in API development, data structures, and testing, Luka implemented an automated test to validate the mapping of OpenAI parameters to the Anthropic schema, ensuring correct referencing of $defs. This work improved schema stability and reduced integration risk for multi-model tool usage. The depth of the solution is reflected in the careful handling of schema definitions and the addition of robust test coverage, supporting reliable downstream development.