We have built a system for augmented reality visualization based on a single head mounted tracking camera. The camera includes an infrared illuminator and works in conjunction with a set of retro-reflective markers that are placed around the workspace. This marker frame configuration delivers excellent pose information, which translates to stable, jitter-free augmentation. In this article, we describe using the same single camera system for tracking relatively small marker clusters, which can be used for tool or instrument tracking. Tracking of such a marker cluster is more susceptible to noise compared to tracking of a marker frame, mainly due to its small image coverage. The sensitivity to noise is studied using Monte Carlo simulations and verified in an experimental setup. We achieved jitter-free augmentation with an optimized cluster design.