As part of a larger project to co-design and create a mHealth tool to support caregivers of children with cancer, we performed a pilot, qualitative study. For this portion of the project, we engaged with caregivers of children with cancer to co-create and refine a low-fidelity prototype of the Children’s Oncology Planning for Emergencies mHealth tool. Testing was accomplished through recorded semi-structured interviews with each caregiver as they interacted with a low-fidelity wireframe using Adobe Xd. Through the engagement of our key stakeholders, we were able to refine the COPE tool to provide the key elements they desired including pertinent patient medical information, checklist for planning when seeking urgent care, and coordination of care with the medical team and other caregivers.