What does a WDT tool do?

It stirs the coffee grounds in the portafilter basket to break up clumps and level the bed. A more even puck resists channeling, so water flows through it more uniformly.

Will it fit my portafilter basket?

The nine needles spread across a standard espresso basket, so it works with common 51mm to 58mm sizes. Stir with the basket dosed as usual, then tamp.

They are 0.4mm and fine by design, so they can bend if pressed hard or dropped. Stir gently through the grounds rather than pushing into the basket.

Does it come with a stand?

Yes. The magnetic stand is included and holds the tool upright between uses.

Is it worth it over a cheaper stirrer?

If you grind your own beans and want repeatable shots, the fine needles and stand make prep tidier than a wire or paperclip. It will not fix an uneven grind or a poor dose.

Does it help with pre-ground coffee?

Less so. Pre-ground coffee is coarser and more uniform, and pressurized baskets are forgiving of clumps, so the gain is smaller than with freshly ground beans.