I may be missing something, but in addition to this threat of prompt injection, you also have to trade trusting the arbitrary MCP server for trusting MCP Defender.

In the default mode, the app will interpose on the communication between, say, Claude, and a local MCP server. It will send the contents of the message (which may include the very sensitive information it is trying to protect) to a remote LLM, which you have to trust. The "scans" will be stored on a log on the server. Not to mention the potential extra delay for every MCP exchange?

This may be more secure, but is it really?