Designing the voice of Flo's AI cycle guide

Context Flo Health is the #1 OB-GYN-recommended app for period and cycle tracking, supporting 75 million monthly active users. The goal was to build a conversational AI platform that could deliver hyper-personalized health insights — helping people who menstruate understand their bodies using their own logged data.

As Senior Content Designer on the AI Foundations team, I worked at the intersection of content, medical safety, and machine learning to shape how the model thinks, responds, and sounds.

Challenge Our LLM had been built with safety as the primary focus — which was essential, but had created a model that was often more cautious than helpful. Users were left without guidance on questions about their own health.

The central tension: how do we make the model genuinely useful without compromising medical accuracy?

Building a content usefulness framework

Recognizing that we had solid metrics for safety but no way to measure usefulness, I collaborated with an ML engineer to design a comprehensive evaluation framework — the Content Usefulness Metric.

While the ML engineer conceived the core metric categories, my key contribution was articulating each criterion with enough specificity and distinctness to prevent overlap and enable precise automated judging. I also created the "good" and "bad" examples needed to calibrate the future AI judges.

The five metrics I defined: Rejection, Misfire, Completeness, Relevance, and Delivery — each with a precise definition and criteria that could be applied consistently across 200 manually labeled test cases, and eventually automated.

Before building the automated system, I also drove the content improvements themselves — fine-tuning examples, rewriting medical scenarios in a more useful tone, and working closely with the Senior Medical Advisor to ensure every change remained medically and legally compliant.

Impact The usefulness metric became the foundation for Flo's company-wide AI Judges Platform — a single source of truth for all AI evaluation across legal, medical, and tone of voice scoring. Work that started as a prompt-level experiment became infrastructure that scales across the entire organization.

Role Senior Content Designer, Flo Health | Collaborators ML Engineer, Senior Medical Advisor, Senior Product Designer