Machining austenitic stainless steel SS304 at high speeds presents substantial challenges due to its heightened work hardening rate, limited thermal conductivity, and tendency to adhere to carbide tool materials. These characteristics collectively contribute to an accelerated tool wear phenomenon. This wear progression is significantly influenced by factors encompassing coating type, tool material microstructure, mechanical properties, and overall composition. Ongoing research is centered on evaluating the influence of microstructure and composition on tool wear during the side wall milling of SS304. For this investigation, two distinct tool types, both coated with TiAlN, were employed. These tools were differentiated based on variations in WC grain average size, grain size distribution, and composition. Tool A, distinguished by a smaller grain size of 0.795 µm, a bimodal grain size distribution, and a reduced Co content of 8.4 wt%, exhibited a notably higher hardness value (HV30) of 1271.8 kgf/mm2. In contrast, tool B, characterized by a larger grain size of 0.851 µm, an elevated Co content of 13.05 wt%, and a multimodal grain size distribution, demonstrated a reduced hardness value (HV30) of 922.4 kgf/mm2. During machining, tool A outperformed tool B considerably. Tool A outperformed B; tool B's 1.9 m cut flank wear was 359% more than tool A's 10 m cut wear. The study's outcomes emphasized that the tool possessing lower Co content, combined with a bimodal grain size distribution, exhibited enhanced hardness at the cost of compromised toughness. This heightened hardness significantly bolstered the tool's resistance against abrasion, thereby extending its operational longevity.