Cutting tool body, cutting insert, and cutting tool

A cutting tool comprising:

• a body;
• and
• a cutting insert provided in the body, wherein
• the body includes
• a front end surface,
• a rear end surface located opposite to the front end surface,
• an outer circumferential surface contiguous to the front end surface,
• a first seating surface contiguous to each of the front end surface and the outer circumferential surface, and
• a second seating surface contiguous to the front end surface and located closer to a central axis than the outer circumferential surface,
• the body is provided with a recess contiguous to each of the first seating surface, the second seating surface, and the front end surface,
• when the front end surface is viewed in a direction from the front end surface toward the rear end surface,
• a length of the recess in a direction perpendicular to a straight line parallel to the central axis and extending along the first seating surface is equal to or longer than three times as long as a length of the recess in a direction perpendicular to the first seating surface and passing through a contact point at which the second seating surface, the recess, and the front end surface contact each other,
• the cutting insert includes
• a top surface,
• a bottom surface located opposite to the top surface, and
• a side surface contiguous to each of the top surface and the bottom surface,
• a ridgeline between the top surface and the side surface has a cutting edge,
• the side surface has
• a first side surface portion contiguous to the bottom surface and inclined at a first angle relative to the bottom surface, and
• a second side surface portion contiguous to the first side surface portion and inclined at a second angle relative to the bottom surface,
• the first angle is larger than the second angle, and
• the bottom surface faces the first seating surface and the side surface faces the second seating surface.