The definition of "agent"

An interesting exchange between Guido van Rossum and Andrej Karpathy a few days ago on Twitter:

Guido van Rossum: I think I finally understand what an agent is. It’s a prompt (or several), skills, and tools. Did I get this right?

Andrej Karpathy: LLM = CPU (data: tokens not bytes, dynamics: statistical and vague not deterministic and precise) Agent = operating system kernel