I'm pretty sure the LLM can use tools while doing arc-agi-3 but it has to the same tools available all the time not an incredibly elaborate custom harness.
To quote someone else from upthread, tool use requires a harness. Without one an LLM as commonly understood is a bare model that receives inputs and directly produces outputs the same as talking to an unaided person.
I'd like to suggest that prior to expressing disagreement you really ought to reread the comment you're replying to and make sure your understanding is correct.
Quoting this for the second time now - tool use requires a harness.
Without a harness the LLM has no ability to interact with the world. It has no agency. It's just spitting out text (or whatever else) into the void. There's no programming tools, no filesystem, no shell, nothing.