Change title of issue to be clear and specific. Customizer means nothing.

Also, you can set the opacity of background color with changing @tooltip-bg. I don't think that you want to change opacity of text.

Thanks for the tip, next time I will be more specific :)

There is still some opacity left, even when changing the tooltip background.
As you can see in https://github.com/twbs/bootstrap/blob/master/less/tooltip.less, the opacity is set separately.

@synlag a little override won't hurt, so just override relevant class in your custom *.less file and compile it, its not a rocket science to override the opacity of tooltip.

[code]
.tooltip {
&.in { .opacity(.4); } // set opacity of your choice here
}
[/code]

I am hoping you know how to compile and where to include this change, good luck.

Thanks for the tip @saas786, I already did that.
Just wanted to let them know that it would be nice being able to set the opacity at the customizr.