Agents run tools in a loop to achieve a goal
2 quotes filed under agent / architecture, newest first.
Harrison’s 4 elements of an agent remain – the system prompt, planning tool, file system, and subgents – describing the core loop. This is the core loop the developer controls with the keyboard. The harness manages everything beyond this, the world the developer sits within.
Harnesses are Situated Agents · Drew Breunig · 14 August 2026