There are any number of tools that are common in any household, that will be necessary in building your mini castle.
Just about the most important tool will be a generator. I bought a little used Toro that had been reconditioned in a little shop on Route 53 in Weymouth. I paid $125.00 and have not had a moment of trouble with it in over a year. A larger generator, and a more efficient one would be good for regular use when your house is finished. But, this one is great when a little extra power might be needed just for the vacuum cleaner or the computer when the sun has not been cooperative in generating power. It runs my compressor and would power a nail gun, circular, table or chop saw. It will keep your lights going into the evening if you want to work late.
Hammers. They come in different weights. There are large framing hammers, tack hammers, and the one you see everywhere that is just for general use. The general rule of thumb is big hammer for big nails and big jobs. Yes they are heavier, but you will ultimately use less energy and suffer less strain if you use a bigger hammer. 21 ounces is great for framing. You may however opt for a pneumatic nail gun. I rather like using a hammer and nails, especially on small jobs...something familiar and Zen about it. Also I resist innovation...a sign of my age no doubt.
Tools for basic construction of the building. Tools for electrical and plumbing discussed elsewhere.
A framing square,
A combination square
An angle copier. A wooden handle with a tightening nut and a sheet metal blade that slides in and out and to various angles to copy or repeat angled cuts.
The longest level you can afford or have space for. The longer they are, the more accurate they are.
A clear plastic tube at least five or ten feet longer than the longest measurement likely on your project. Filled with water, the water seeks its own level no matter how far apart or how you hold it or coil it on the ground. Great for leveling your foundation, sonotubes, sills, ridgepole, etc. This will be more accurate than the best and longest level.
A ten inch circular saw for rough cuts.
A table saw for rip cuts.
A good quality chop saw for complex angle cuts and for accuracy that cannot be achieved by a circular saw.
There may be instances where you do not want to be handling a power tool. the following hand saws will help.:
A crosscut hand saw. You will recognize a crosscut saw by balancing a pencil along the length of the saw blade on the teeth. A crosscut saw has splayed teeth so there is a place to for it to rest. It cuts easily across the grain of wood.
A rip hand saw. The teeth are in line so you cannot balance a pencil on the teeth. It cuts along the length of the grain of a piece of wood.
Tin snips for cutting sheet metal, mesh, screening etc.
A razor knife.
A chalk line.
A crow bar or cats paw or flat wonderbar,
A six foot iron pike(a little hard to find) will help you jockey large stones or even the entire building into place inch by inch.
Flat carpenter's pencils.
A good quality metal measuring tape. 25 feet is good.
Two 25 foot aluminum ladders
A Plastic cement mixing tub or rented cement mixer.
A long handled round nosed shovel,
A Short handled shovel with D handle.
A Post hole digger or gas powered auger.
A Heavy duty wheelbarrow.
A mason's trowel
A 1/4 inch power drill and drill bits.
Philips and flat screwdrivers in various sizes and/or screw bits for the drill.
Several heavy duty extension cords.
Wire cutters and pliers.
Staple gun and 1/2 inch staples.
1/2 and 1 inch wood chisels.