The El Niño-Southern Oscillation (ENSO) is the dominant mode of interannual variability in the tropical Pacific and has far-reaching impacts on climate around the world. It is therefore key to ensure the correct simulation of ENSO in state-of-the-art climate models. A community-wide synthesis of metrics to evaluate the performance, teleconnections and processes of ENSO in coupled GCMs is now underway, led by the ENSO Metrics Working Group of the International CLIVAR Pacific Panel. This collaboration has already produced a new software package, written in Python, to facilitate multi-model diagnosis, evaluation, and intercomparison of ENSO simulations. The package assists in (1) identifying common model biases and their sources to guide model improvements; (2) assessing progress made from one generation of models to the next; (3) identifying models that are best suited for particular tasks; and (4) revealing emergent constraints among the diverse model responses to future climate change. The ENSO package is designed to interface with existing model evaluation software architectures, including PCMDI Metrics Package and ESMValTool. The capabilities of the package are demonstrated through application to the CMIP5 archive. A paper documenting the package and its application to the CMIP6 simulations is planned for the near future.