There's no substitution IF statement to count the number of characters nor a substitution to cut it short. Best I can suggest is to use CSS and text-overflow or using a CB Query Field to query for a limited number of characters from the description field column. The CSS example is as follows.
Code:
.cbUserListFC_FIELD_NAME_HERE {
display: inline-block;
max-width: 100%;
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap
}
It works by forcing the text to single line display, setting the max width so it won't overflow its container, then adding overflow handling. You can't really specify how many characters it'll be but it's better than it filling up the page with a very long description.
Another alternative is to use jQuery/JS to modify the DOM after page load. The JS could be added to the page using CB Auto Actions and its Code action.