Worked on the dotnet/command-line-api repository to enhance command-line argument handling and improve the clarity of error messaging for CLI users. Focused on refining how missing arguments are reported, the work introduced error messages that specify the exact argument name and improved the fallback logic for HelpName to ensure consistent guidance. Expanded unit test coverage to validate scenarios involving multiple missing arguments, supporting more robust error handling. All changes were implemented in C# with an emphasis on code maintainability and clarity. The approach prioritized user experience and downstream tool integration, resulting in a clearer and more reliable command-line interface.