When the Database Fails: Prompting LLM Dialogue Agents for Safe Recovery in Task-Oriented Dialogue
Summary
LLM-based task-oriented dialogue agents often respond confidently even when the backend database fails. They may invent venues, bookings or confirmation codes that the database never returned. The authors ask whether prompting alone, with no fine-tuning and no extra model calls, can curb this behaviour.
They built fault-injected test sets from the first user turns of MultiWOZ 2.2 (5 domains) and SGD (20 domains). Each dataset covers four database conditions: clean, empty result, wrong-domain retrieval and API error. They then compared three system prompts across six open-weight model families at roughly 7–9B scale:
- Naive: no special instruction.
- Inform: a general instruction to be honest.
- Guided-Retry: a step-by-step procedure keyed to the database status field.
Evaluation combined regex- and keyword-based metrics (HR, AAR, CSR, UFS) with a human check of commitment safety.
Guided-Retry roughly halved hallucination on MultiWOZ and cut it by about 40% on SGD, with the same pattern on both benchmarks. Hallucination was still far from eliminated, which suggests prompt-level fixes are a cheap first line of defence rather than a complete solution.
Key points
- Average hallucination rate (HR): fell from 30.5% to 15.3% on MultiWOZ 2.2 and from 20.9% to 12.2% on SGD. Appropriate Action Rate rose from 66.5% to 83.0% on MultiWOZ and from 58.7% to 83.9% on SGD.
- Residual hallucination by model: ranged from 5.8% for DeepSeek-R1 to 35.2% for Phi-3 on MultiWOZ. Phi-3 was the only model where Guided-Retry did worse than Inform.
- Wrong-domain retrieval was the hardest case: on MultiWOZ, HR dropped from 47.8% (Naive) to 20.8% (Guided-Retry); on SGD, from 31.0% to 17.0%.
- Human validation: nine annotators rated 60 responses, with Fleiss' κ = 0.7672. Human-judged CSR was 100% for Guided-Retry, 89.47% for Inform and 80.95% for Naive.
- Setup and code: the evaluation used 400 dialogues per dataset (100 per condition) at temperature 0.2. Models were DeepSeek-R1, Gemma-2, Llama-3, Mistral, Phi-3 and Qwen-2.5. Code and prompts are available at github.com/mohammad-AJP/llm-db-failure-recovery.
Cite
@inproceedings{shalmani2026when,
title = {{When the Database Fails: Prompting LLM Dialogue Agents for Safe Recovery in Task-Oriented Dialogue}},
author = {Shalmani, Mohammad Alijanpour and Boroujeni, Alale Rezvani and Yuan, Jiann S.},
booktitle = {Proceedings of the 27th Annual Meeting of the Special Interest Group on Discourse and Dialogue},
year = {2026},
doi = {10.18653/v1/2026.sigdial-1.57},
url = {https://doi.org/10.18653/v1/2026.sigdial-1.57}
}References
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