Single Point Incremental Forming (SPIF) has emerged as a flexible and cost-effective technique for producing complex sheet metal parts. However, its industrial application is often limited by issues related to surface quality. This study examines the impact of tool geometry on the surface integrity of the AA6061-T6 aluminum alloy. The research novelty lies in the innovative eccentric tool with a variable radius (ETVR), which we compare to two conventional hemispherical tools with radii of 5 mm and 10 mm. Truncated cones were formed under the same process conditions, and their quality was assessed by measuring surface roughness and microhardness along the cone’s generatrix in both the rolling direction and the transverse direction. Additionally, microchip analysis and visual inspections were conducted. The results reveal distinct differences in the surface morphology, evolution of roughness, and distribution of microhardness among the three tools. The SS5 tool produced the highest level of hardening but also resulted in significant surface deterioration. In contrast, the SS10 tool generated smoother surfaces with moderate hardening, while the ETVR tool struck a balance between surface uniformity and enhanced hardness. Statistical analyses, using t-tests, confirmed the significance of these findings. This study offers new insights into tool design for SPIF, highlighting the trade-offs between surface quality and material strengthening.