MCP's (Model Context Protocol) most meaningful architectural contribution isn't tool-calling or context injection, but rather keeping authentication flows outside the agent's context window and execution harness entirely. This matters because it reframes MCP as potentially just a secure auth gateway pattern, which is a cleaner and more trustworthy separation of concerns than bundling auth logic into agent prompts or orchestration code.
TLDR: The Properties Pattern (flexible key-value pairs on objects, also called the Prototype Pattern) is a legitimate, powerful modeling approach that rivals OO, relational, and XML design — not a lazy hack. It shines when your schema is volatile or unknown upfront, trading some type safety and performance for extreme flexibility. Dismissing it as "just name/value pairs" causes engineers to over-engineer rigid class hierarchies or schemas where a simple property bag would have been the right tool.