Agent Systems: Exception Handling and Recovery

Problem

Tools fail, retrieval returns nothing, output violates a schema, services time out, and plans become invalid. Treating every failure as another prompt hides the actual state of the system.

Intent and structure

action → classify failure → retry / repair / fallback / escalate / stop

Classify failures as transient, structural, semantic, permission-related, or mathematical uncertainty. The category determines the recovery policy.

Recovery contract

Preserve the failed artifact, error, inputs, attempt count, and checkpoint. Retry only when the operation is safe and bounded. Repair malformed structure without silently changing content. Fall back to a simpler method only when its quality limits are explicit.

Mathematical rule

An unresolved gap is a valid terminal state. Never convert it into a successful- looking summary merely because a later generation step is fluent.

Forces and failure modes

Recovery improves availability but can amplify side effects, duplicate work, or loop forever. Use idempotence, exponential backoff where appropriate, retry limits, circuit breakers, and human escalation.

Figure

Figure: failures are classified and routed to bounded retry, repair, fallback, escalation, or safe stop.