Agent guardrail re-reads facts before irreversible actions, cuts false alarms from 50% to 0%
Professional-Mine681 · reddit · 2026-10-30
A developer followed up on a Reddit discussion about stopping agents from multi-step mistakes—where each tool call looks fine but the sequence goes wrong—with a working first version.
Mechanism: right before an irreversible action runs, the guardrail re-reads the facts that action depends on and blocks if a relevant one changed since approval. A companion benchmark reports catch rate and false-alarm rate separately.
Early numbers (23 scenarios, two tools):
- Block-on-any-change policy: 50% false-alarm rate
- Checking only dependent facts with bounded field drift: 17%
- With conservative normalization: 0% false alarms, no loss in catch rate
- Runs fully on a local qwen2.5-7b model
Known gaps (disclosure-by-combination, lost-ack-retry) are documented in the benchmark. The author asks the community for real-world examples of benign fact changes and whether block/allow boundaries can be written per tool or always need human judgment.
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