I think you lack imagination, but I'm not going to post ideas here for novel weapons that would render the humans' existing defenses and deterrence strategies ineffective.
It's worth pointing out that the humans do not have planet-killer weapons, not even biosphere-killing weapons. They could destroy civilization, but not the planet or even the species. You can make straightforward calculations showing that we already know how to build such weapons, but we haven't.
As for tools, alcohol, tobacco, fentanyl, pornography, monotheism, warfare, gambling, and money itself are "tools wielded by humans", but they still seem to get into a lot of trouble where it seems like the humans are the ones being "wielded" by the tool. And neither monotheism nor gambling is smart enough to write a compiler for me, much less choose persuasive tactics according to my personality type. A lot of humans' basic survival instinct seems to fail or even work backwards in the presence of these "tools".
> It's worth pointing out that the humans do not have planet-killer weapons, not even biosphere-killing weapons.
?? We for sure have enough nukes to completely obliterate ourselves. And the ensuing nuclear winter and ecological collapse would probably destroy almost anyone who survived the initial blast and fallout.
Can you explain how exactly an AI would develop a novel planet-killing weapon without anyone noticing and pulling the plug? Like I seriously don’t understand this argument.