Open any AI chat tool and run a mini ReAct cycle: (1) goal in 8 words (2) one action (3) observe: did a checkable output appear? (4) a second action based on that observation. You're done when you've written the observation line in 12 words or less.
How-to · AUT · AUT.4
ReAct loops vs marketing 'loops'
When someone says 'agent loops,' check whether they mean the plain ReAct cycle (act → observe → act) or a product buzzword.
Worked example
Simon Willison points out that the basic agent loop from the 2022 ReAct paper may be exactly what people mean when they say 'loops' again. That's genuinely useful — you can test a loop without buying a whole platform. Act, observe a checkable result, then act again. No observation step? Then it's not really a loop — it's just a longer prompt.