Definition. tool interaction [yao2023react, Section 2] [ftip-004R]

A ReAct interaction alternates model-generated reasoning and actions with observations returned by an external interface. The observation is appended to the next model context, so subsequent actions may depend on earlier tool results.

A decoded action belongs to \(\mathcal A\) in the declared interactive task realization; the transition--observation kernel of Definition [ftip-001Z] returns the next observation. The cited construction does not by itself fix a sandbox, reward, or training algorithm.