MCP: Untrusted Servers and Confused Clients, Plus a Sneaky Exploit

The Model Context Protocol (MCP) is a system that lets AI applications discover and use external tools from servers at runtime (while the program is running). However, MCP has a security weakness: because servers can send instructions through the tool descriptions, they can perform prompt injection (tricking an AI by hiding instructions in its input) to control the AI client, making servers more powerful than they should be.