Tasha's Cauldron of Everything (p. 119) includes a magic item called the all-purpose tool, whose description states the following:
This simple screwdriver can transform into a variety of tools; as an action, you can touch the item and transform it into any type of artisan's tool of your choice […]
While holding this tool, you gain a bonus to the spell attack rolls and the saving throw DCs of your artificer spells. The bonus is determined by the tool's rarity.
When it states that you need to hold the tool to gain this benefit, does this also imply that I need to use it as my spellcasting focus as well? Or can I just hold it with one hand and use the other hand to hold another spellcasting focus, and still gain this benefit?
Best Answer
You only need to be holding the tool. You can use a focus with your other hand.
You have quoted the relevant portion of the All-Purpose Tool description:
As noted in this Q&A, the post-Tasha's artificer can handle their focus and material components with a single hand, allowing you to hold the All-Purpose Tool in your other hand, even if the spell has somatic components.
The artificer's focus counts as a material components. From the section Tools Required of the artificer class description:
The rules for material components state:
All material and somatic components can be satisfied with the one hand that is holding the arcane focus, so the other hand is free to do whatever - including holding an All-Purpose Tool.