From Old English 'tōl' (instrument), from PIE *dew- (to do) — etymologically a 'doing-thing.'
A device used to carry out a particular function.
From Old English 'tōl' meaning 'instrument, tool, weapon,' from Proto-Germanic *tōlą, from PIE *dew- (to do, make). A tool is literally a 'doing thing' — something that helps you do. Key roots: *dew- (PIE: "to do, make, perform").
'Tool' and 'do' likely share the same PIE root *dew- — a tool is a 'do-thing,' an instrument for doing. The connection is perfectly logical.