Stonecutting and Masonry
In his 1982 book "Castle," David MacAulay described the how stones used in castle-building must be quarried, then shaped into their final forms (for example, wall slabs and floor tiles).
Stonecutters would use a saw to quarry the raw stone. They would use wedges, crowbars, pickaxes and hammers to cut the block to its square shape.
Woodworking
A medieval castle might include wooden floors, doors, paneling, rooves and drawbridges. Builders would cut lumber specifically for the project, and woodworking began with cutting a tree from the surrounding forest, and ended with fine finish work.
Lumberers would use a double-handled saw to fell a tree, then rasps and adzes to debark and shape the lumber.
Woodworkers used handsaws to refine the lumber, to make small wood cuts and for more delicate woodworking.
They used an augur, a hand-held drill that twisted like a screwdriver, to create peg-and-joist joinders. They might also use a brace and bit, a hand drill with a "U" in its handle, to drill holes.
Finally, they used chisels for shaping and cutting designs into the wood or split the wood.
Measurement
Medieval builders used knotted ropes to space floor joists or to measure stone for quarrying. A rope with 13 equally spaced knots created a "ruler" of 12 equal measurements. Even if the tools varied from one castle to the next, using a consistent set of ropes made for consistent measurements on one castle.
They might also use a measuring stick; again, the measurement might be different from one project to the next, but be consistent on the project.
Medieval builders used primitive versions of levels and squares. The level was an inverted V made of wood, with a built-in plumb line.
Smithing
Blacksmiths would be on hand to create hinges, bars for windows, and any hand tools the builders needed. The smith's tools are well-known: the anvil, bellows and hammer.