Displaying character count by Title and Meta Description fields would help ensure the lengths are optimized for search (SEO) and social sharing. It would also save me the hassle of copying and pasting into others tools to get the count. In addition to char count, a link/lightbox to preview the snippet for search would be really handy.
References:
https://moz.com/blog/new-title-tag-guidelines-preview-tool
https://moz.com/blog/i-cant-drive-155-meta-descriptions-in-2015