Abstract: A machining tool (1) comprises a clamping section (2), which extends along a central axis (M), a cutting section (3), which adjoins the clamping section (2) and has a nominal diameter (DN), and at least one cooling duct (4), which preferably extends in the clamping section (2) and in the cutting section (3), wherein the cross-sectional shape of the cooling duct (4) is arranged in a cross-sectional region (Q) of the respective section (2, 3) in which the equivalent stress under a machining load has a value which is as small as possible, and/or wherein the cross-sectional shape of the cooling duct (4) is defined by an inner curve segment (5), an outer curve segment (6), which is arranged at a distance from the latter, and by means of two tangents (7) connecting the two curve segments (5, 6).