Normally git-annex does not retrieve file contents when checking out a tree. In some use cases, it makes sense to always have the contents of files available after a git checkout or git update. This can be accomplished by installing the following as .git/hooks/post-checkout

#!/bin/sh
# Uses git-annex to get all files in the specified directories
# (relative to the top of the repository) on checkout.
dirs=.
top="$(git rev-parse --show-toplevel)"
for dir in "$dirs"; do git annex get $top/$dir"; done

By default, all files in the whole repository will be made available. The dirs setting can be configured if you only want to get files in certian directories.