A tool body (1) has a coupler for engagement with any of a variety of tool heads such as a spade head (3), and a hatchet head (4). A tool comprising the body (1) and a tool head (3-10) is a hammer action tool. It may be used as a fork, spade, chisel, hatchet, or any tool which would benefit from a hammer action. A tubular shank (21) and a hammer (22) are together a hammer weight which is pushed down by the user until it hits a receiver (23), driving the tool head. A spring (24) returns the hammer (22) and a shank (21) back up to the start position ready for the next hammer action. It also acts to push the tool head out against a work surface for overhead work such as chiseling. A spring (25), acting between a hammer impact part (22) and the handle (21, 27) takes the shock out of the impact for the user's hands. The shank (21) and the hammer (22) slide up and down together on the box-section receiver tube (32). A safety locking mechanism has a catch (30) biased to automatically lock the hammer unless the user presses a trigger in the handle.