Agent workflows · 2026-09-22
Error handling and fallback strategy in AI agents
What should happen when an agent's tool call fails: the decisions behind retrying, switching to an alternative tool, and stopping the task safely.
An agent has three options when it hits an error
The architecture covered in the AI agent for Turkey guide defines which tools an agent uses in what order; but what happens when a tool call unexpectedly returns an error is a separate design decision. There are three basic options: retry the same tool, switch to an alternative tool or model, or stop the task safely and report the state.
Rather than blindly picking one of these three, the decision should follow the error type; not every error deserves the same response.
Which error deserves which response
A transient network error or timeout is suitable for retrying the same request after a short wait; persistence usually resolves this kind of error. An error like 'not authorized' or 'resource not found' returned by a tool, on the other hand, is not fixed by retrying; in that case it's more correct for the agent to try an alternative path (a different tool, a different query) or stop the task and notify the user.
Setting an upper limit on retry count is a critical safety measure; unlimited retrying can turn a transient error into an infinite loop and send both cost and latency out of control.
- Transient error (timeout, 5xx): a limited number of retries makes sense.
- Permanent error (authorization, not found): use an alternative path or safe stop instead of retrying.
- Always set an upper retry limit; never allow an unlimited loop.
A safe stop beats a silent failure
When an agent has exhausted every option, it should clearly report at which step and why it stopped, rather than silently leaving the task half-done. This is the only reliable signal that lets a user or a monitoring system notice the problem and intervene; a silent failure gets noticed much later.
Frequently asked questions
Should an agent automatically retry on every tool error?
No. Retrying only makes sense on errors considered transient (timeouts, temporary capacity). On permanent errors like authorization or format issues, retrying does not fix the problem — it only adds latency.
Is switching to an alternative tool always possible?
No, it depends on the task. If there is no alternative tool or path, the correct thing for the agent to do is stop the task safely and clearly report the state.