In November 2025, Michael Naujoks enhanced the modelcontextprotocol/csharp-sdk by implementing persistent OAuth access token caching, focusing on improving authentication reliability for client applications. Using C# and leveraging OAuth protocols, he designed a mechanism that stores access tokens beyond the HTTP transport lifetime, addressing issues with token expiration during long-running sessions. This approach reduced token-related failures and minimized friction in token refresh processes, increasing the resilience of client integrations. Michael applied his skills in authentication and unit testing to ensure robust functionality, delivering a targeted feature that addressed a specific reliability concern without introducing new bugs or regressions to the codebase.