The CLI needs a proper --help and man page

[NightMachinery]

Adding the examples is a good first step.

[NightMachinery]

My own summary of the examples:

googleimagesdownload --keywords "Polar bears, baloons, Beaches" --limit 20
googleimagesdownload -k "Polar bears, baloons, Beaches" -l 20

--format svg
-co red : To use color filters for the images
-u <google images page URL> : To download images from the google images link
--size medium --type animated
--usage_rights labeled-for-reuse
--color_type black-and-white
--aspect_ratio panoramic
-si <image url> : To download images which are similar to the image in the image URL that you provided (Reverse Image search).
--specific_site example.com