During December 2025, Mihály Gyarmathy enhanced the modelcontextprotocol/typescript-sdk repository by focusing on TypeScript support for Express applications. He implemented an Express Type Definitions Enhancement, directly adding @types/express-serve-static-core as a development dependency to reinforce type safety in middleware and routing. Working primarily with TypeScript, JavaScript, and Node.js, Mihály improved the reliability and clarity of type definitions, which benefits downstream SDK users by making integrations safer and more predictable. He collaborated with another contributor to ensure the changes aligned with TypeScript standards. The work addressed type safety concerns, though it was limited in scope to a single feature update.