Lesson 21 — Error handling and retries

When things go wrong

Two things fail all the time in agents:

1. The model returns bad output — prose instead of JSON. Fix: catch the error, add a message like "Reply with valid JSON only", and retry (ask again), up to a limit.
2. A tool raises an exception — dividing by zero, a missing file, a site that is down. Fix: catch it and turn it into an observation, such as "error: ZeroDivisionError: division by zero". The model reads the error and can try something else.

try:
    return risky()
except Exception as err:
    return "failed: " + str(err)

type(e).__name__ is the error's class name; str(e) is its message.

Why it matters: a crash ends the whole run. An error the model can see is just one more step.