The Model Context Protocol (MCP) is an external function calling mechanism used with Large Language Models (LLMs). Despite its evolution, authentication has consistently been a challenge. The author of the agenda.dev project, who was using Better Auth, realized that the auth UUID or bearer token could be accessed in plaintext via the client provider's MCP.json file. This issue led to a search for an MCP OAuth solution, which ultimately resulted in collaborating with Bereket Engida and Andrew Qu from Vercel to implement a simple authentication mechanism using their `@vercel/mcp-adapter` package. This package provides a straightforward way to set up an MCP server within a Next.js project, making it easy to define tools for the LLM to use. The implementation requires minimal code changes, with only 3 files and under 10 lines of code needed to be modified. The solution uses OAuth to handle authentication, allowing users to access their data securely.