Building Custom MCP Clients for Next.js Serverless: Engineering Guide

The Model Context Protocol (MCP) enables AI agents to interact with local tools, but deploying it on serverless platforms like Vercel or AWS Lambda requires shifting from local stdio to networked transports. This guide explains how to use SSE and HTTP POST to bridge ephemeral serverless functions with stateful MCP sessions. It covers solving the timeout trap and enforcing data integrity with Zod validation.