Always good to be paranoid.
Even MCPs are not safe. For example Notion injected ads [1] to its official MCP connector to advertise products mid-task.
[1]: https://old.reddit.com/r/ClaudeAI/comments/1w9dluw/notions_o...
Whoever came up with that brilliant idea is probably paid twice what I am
MCP is SOAP-XML without the contract or formal language, it's hilarious