Assurance cases capture the argumentation that a system is safe by putting together pieces of evidence at different levels of abstraction and of different nature. Managing the interdependencies between these artefacts lies at the heart of any safety argument. Keeping the assurance case complete and consistent with the system is a manual and very ressource consuming process. Current tools do not address these challenges in constructing and maintaining safety arguments. In this paper we present a tooling prototype called Safety.Lab which features rich and deeply integrated models to describe requirements, hazards list, fault trees and architecture. We show how Safety.Lab opens opportunities to automate completeness and consistency checks for safety argumentation.