Agents are just not deterministic. You will see wierd things like in one thread an agent simply says it cannot access a CLI tool for whatever reason. You inspect the call, it worked just fine in another thread. You eventually shrug your shoulders and close the thread, pick up from another instead of having the agent flail around some obvious BS for hours and hours.

Just because they can run tools, doesn't mean they run them reliably. Running tools is not a be all and end all of the problem.

Amdahl's law is still in play when it comes to agents orchestrating entire business processes on their own.