IIUC the point is that the agent has the ability to modify itself? So one possible term could be "self-evolving" or "self-modifying agent".
Any agent that accepts "work in this working directory" (which AFAIK, all of them do) have had this ability, even the initial GPT2/3 experiments around matching LLMs with primitive tool-calling.
Any agent that accepts "work in this working directory" (which AFAIK, all of them do) have had this ability, even the initial GPT2/3 experiments around matching LLMs with primitive tool-calling.