You don't want to give the agent a raw key, so you give it a dummy one which will automatically be converted into the real key in the proxy.
So how does that help exactly? The agent can still do exactly what it could have done if it had the real key.
For one thing, it cannot leak secrets between services.
Is that really a problem? All the examples on the repo page themselves show LLMs running unintended operations on the "correct" service and messing up your data. And that is very much still going to happen with this wrapper. If anything it is going to provide a false sense of security.
it cannot email your secret key to an attacker because of prompt injection etc.