How should undo actions be worded?

Question

I am planning to add a tooltip to our app's Undo and Redo buttons that will describe what action will be undone or redone when it is clicked. How should they be worded?

Here are some examples:

• Undo set color to black
• Undo change color to black
• Undo changing color to black

Or another situation:

• Undo underline text
• Undo underlining text
• Undo set underline

And another:

• Undo resize (2 objects)
• Undo resizing 2 objects
• Undo multiple object resize

Are there any existing policy guides for how these actions should be worded?

Answer 1

Pixelmator, OmniGraffle and many more (Mac) apps name the undo action after the tool that has been used:

• Undo Crop
• Undo Selection
• Undo Smudge
• Undo Paint Bucket
• Undo Delete

But I also saw "Undo Set ...":

The first option in your three examples seem to come closest to what these apps do but if you need to add details like the kind of color you can do something like:

Undo Set Text Style (bold)

The tool (Set Text Style) with capital first letters and the value between parentheses or, if it's a color, as a small square:

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Answer 2

Personally, I've never seen multiple undo buttons in the same page/screen. In a case when you have multiple types of actions, I find the Photoshop History window to be a nice and intuitive pattern :

They allow to click on any action in the stack to get directly to that point and undo all the actions up to that point. Plus they state(text) what the actions were. You can combine that with a single "Undo" button, that will just undo the last action(the custom text will be in the window)

Answer 3

The common working of the undo function is chronological. 'Going back in time' requires less cognitive effort than thinking about what particular action you want to undo (which in most cases is your last action). Therefor, there is only one undo button in most cases. The step backward functionality in Photoshop works slightly different as Boranas pointed out and is ironically undo-able on itself (this enables you to switch between two states of the design on different points in time).

Now, this functionality sound very easy, but it takes a lot of effort (and thus resources) to implement it. So, if you're short on resources, maybe you could try to solve this problem with text. Instead of calling it 'undo', why not: reset [name of property to reset]. It's not weird to have a different buttons for resetting different things.