If multiple tools are included in your toolbelt, you should be able to enable automatic tool swapping. While enabled, when you look at a block, it will attempt to choose a tool that would be able to mine that block.

If no tool is available that would mine the block, or if the block you are looking at has no ideal tool, it will do nothing.

There are a lot of ways this could be implemented, but this is what I think would be the most ideal:

1. You hold a tool.

2. Open the radial menu and shift click an empty slot.

3. The tool you held while doing step 2 would become the default tool. If you look at a block that can't be mined with your default tool but can be mined with one on your toolbelt, it would immediately switch to that tool. When you look away, it switches back to your default tool.

This could be expanded to include cases such as equipping shears when looking at sheep, but I think this would work for the vast majority of situations. Shears, wrenches and other unique tools would be nice, but they aren't used nearly as frequently as a pickaxe or a shovel.

A variant to Middle-Clicking would be a nicer approach to this, appropriate with 'picking' a block, or just an auto switch on an attempt to use the tool.