Developed and delivered Enterprise Single Sign-On with Cross-App Access for the modelcontextprotocol/typescript-sdk, focusing on enabling enterprise customers to authenticate via their organization’s identity provider and securely access protected MCP servers. This feature was implemented using TypeScript and centered on a two-step OAuth flow, aligning with SEP-990 Enterprise Managed OAuth standards. The work consolidated cross-application authorization within the SDK, streamlining onboarding and centralizing access control for enterprise environments. By leveraging API integration and advanced authentication techniques, the solution enhanced both security and user experience, providing a robust foundation for enterprise readiness without introducing new bugs during the development period.