Build a ReAct Agent That Calls Real APIs: End-to-End in Python
· 7 min read
The ReAct pattern (Reason → Act → Observe → loop) is the workhorse of modern agents. It is also where most "hello world" tutorials end and real engineering begins. What does the loop look like when the tools actually call external APIs? When the API rate-limits? When it returns malformed JSON?
Here is the end-to-end pattern, with the failure modes baked in.