Let's be a bit more specific -- that is one important point of the article, that as soon as the "Tool AI" definition becomes more specific, the problems start to appear.

We don't want just a system that finds a route between points A and B. We have Google Maps already. By speaking about AGI we want a system that can answer "any question". (Not literally, but it means a wide range of possible question types.) So we don't need an algorithm to find the shortest way between A and B, but we need an algorithm to answer "any question" (or admit that it cannot find an answer), and of course to answer that question correctly.

So could you be just a bit more specific about the algorithm that provides a correct answer to any question? ("I don't know" is also a correct answer, if the system does not know.) Because that is the moment when the problems become visible.

Don't talk about what the Tool AI doesn't do, say what it does. And with a high probability there will be a problem. Of course until you tell what exactly the Tool AI will do, I can't tell you how exactly that problem will happen.

This is relevant:

Marcus Hutter is a rare exception who specified his AGI in such unambiguous mathematical terms that he actually succeeded at realizing, after some discussion with SIAI personnel, that AIXI would kill off its users and seize control of its reward button.

Please note that AIXI with outputs connected only to a monitor seems like an instance of the Tool AI.