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Main Authors: Mu, Norman, Lu, Jonathan, Lavery, Michael, Wagner, David
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.12197
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author Mu, Norman
Lu, Jonathan
Lavery, Michael
Wagner, David
author_facet Mu, Norman
Lu, Jonathan
Lavery, Michael
Wagner, David
contents System prompts have emerged as a critical control surface for specifying the behavior of LLMs in chat and agent settings. Developers depend on system prompts to specify important context, output format, personalities, guardrails, content policies, and safety countermeasures, all of which require models to robustly adhere to the system prompt, especially when facing conflicting or adversarial user inputs. In practice, models often forget to consider relevant guardrails or fail to resolve conflicting demands between the system and the user. In this work, we study various methods for improving system prompt robustness by creating realistic new evaluation and fine-tuning datasets based on prompts collected from from OpenAI's GPT Store and HuggingFace's HuggingChat. Our experiments assessing models with a panel of new and existing benchmarks show that performance can be considerably improved with realistic fine-tuning data, as well as inference-time interventions such as classifier-free guidance. Finally, we analyze the results of recently released reasoning models from OpenAI and DeepSeek, which show exciting but uneven improvements on the benchmarks we study. Overall, current techniques fall short of ensuring system prompt robustness and further study is warranted.
format Preprint
id arxiv_https___arxiv_org_abs_2502_12197
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Closer Look at System Prompt Robustness
Mu, Norman
Lu, Jonathan
Lavery, Michael
Wagner, David
Computation and Language
Artificial Intelligence
System prompts have emerged as a critical control surface for specifying the behavior of LLMs in chat and agent settings. Developers depend on system prompts to specify important context, output format, personalities, guardrails, content policies, and safety countermeasures, all of which require models to robustly adhere to the system prompt, especially when facing conflicting or adversarial user inputs. In practice, models often forget to consider relevant guardrails or fail to resolve conflicting demands between the system and the user. In this work, we study various methods for improving system prompt robustness by creating realistic new evaluation and fine-tuning datasets based on prompts collected from from OpenAI's GPT Store and HuggingFace's HuggingChat. Our experiments assessing models with a panel of new and existing benchmarks show that performance can be considerably improved with realistic fine-tuning data, as well as inference-time interventions such as classifier-free guidance. Finally, we analyze the results of recently released reasoning models from OpenAI and DeepSeek, which show exciting but uneven improvements on the benchmarks we study. Overall, current techniques fall short of ensuring system prompt robustness and further study is warranted.
title A Closer Look at System Prompt Robustness
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2502.12197