Cascading Agent Failures
Anti-pattern: build a multi-agent system where one agent's failure or hallucination propagates as input to peers, until the whole system has drifted.
Problem
A localised failure — a hallucinated fact, a corrupted memory write, a tool error misinterpreted as success — propagates through the message graph. Each downstream agent integrates the failure into its own reasoning and emits a confidently-wrong output that the next agent in turn treats as input. The system fails as a unit, not as individual agents; classical per-agent retries do not help because the inputs are themselves poisoned.
Solution
Don't. Apply per-edge validation between agents — type checks, schema validation, confidence thresholds. Use external-critic or agent-as-judge on intermediate messages, not just final output. Cap retry-fan-out so one root failure cannot recursively spawn more agents. See unbounded-subagent-spawn and unbounded-loop for related shapes.
When to use
- Never. Cite when reviewing multi-agent topology.
- Add per-edge validation, confidence thresholds, and circuit-breakers between agents.
- Bound retry depth so root failures cannot recursively expand the agent graph.
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