Following a series of unplanned generation outages involving unexpected behaviors from inverter-based resources (IBRs), there has been a significant need for monitoring, control, and protection functions that can help system operators more rapidly understand and respond to these unexpected behaviors. This paper presents the IBR-rich transmission system datakit (IRTSD), which is focused on disturbances in transmission systems with high IBR penetration and consists of a dataset, power system model, and automation scripts. The data consists of 5500 events and 1.4M labelled signal recordings of power system disturbances produced using an electromagnetic transient model of a transmission system with roughly 40% IBR penetration. While the transmission system is small topologically, detailed models are used for IBR controls, conventional generators, and phasor measurement units (PMUs), resulting in a high-fidelity representation of a wide variety of power system phenomena from 0.5 Hz to 4 kHz. Events simulated include both the commonplace (e.g., stepping of voltage controls) and the emergent issues (e.g., forced oscillations or unexpected momentary cessation at an IBR plant). This paper covers the design and methodology behind the dataset, model, and automation scripts. It also provides an overview of the dataset, highlighting current research problems that the data and toolset are applicable to. The dataset, along with the models and automation scripts used to generate the data, are available to all users on IEEE DataPort and make the dataset easy for others to study, modify, and extend.