Trust in Large Language Model (LLM) chatbots depends not only on what these systems do but also on how their behavior is governed and communicated. We present Trust Mediator, a workbench that enables service owners to elicit chatbot principles and run persona-driven evaluations. To assess this approach, we introduce three analytic metrics: specificity, coverage, and coherence.
In an exploratory between-subjects study, we compared manual and assisted principle authoring. Participants in both conditions viewed principles as useful for governing and assessing chatbot behavior. Assisted authoring was generally perceived as more supportive and tended to broaden coverage. Manual authoring required more effort but yielded principles that were significantly more specific, with trends toward greater coherence and improvements in chatbot responses.
These findings highlight the complementary strengths of assisted and manual pathways. Beyond their analytic role in this study, the metrics themselves point to future use as design objects for principle-authoring tools.

