You can build a plain english (markdown file) describing exactly what the agent's role and purpose is.
with new instructions to help them complete their tasks.
Yeah, the enthusiasts changed the name "prompting" to other things so they could have something new to talk about. The models still provide output in response to input even if someone has added some additional software layers and buzz words to impede your understanding.
Tell me you don't know without telling me you don't know. You just did.
Of course it's input and output. So is an operating system, and that doesn't make it a rebranded transistor.
A prompt is one call and a human reads the result.
An agent runs a loop: the model calls a tool, something actually executes, the result comes back as the next input, and the model decides what to do next and when it's done. Nobody types between those steps. Yes, there are still prompts in there. The model itself is writing most of them.