Topic on Project:Support desk

It have to be added manually.

As described in the page - Help:Images#Syntax - the alt text is " created automatically from the caption, stripped of formatting."

I have some really lengthy captions for some of the images, so will they produce that large alt texts is no alt text is manually created? Or does the program follow some kind of algorithm to select the alt text form the image?

No. If you want different alt text you have to specify it.

Got it. Thank you so much for confirming.