What is the max number of characters allowed in title, description and keywords in featured results?

The maximum number of characters that can be given in title is 150 

The maximum number of characters that can be given in description is 250

The maximum number of characters that can be given in keywords is 2200

Please note that the above limit is for UI Featured result creation. 

Using API it is possible to add a title with more than 255 characters though we would not recommend the same.

To learn more on featured results read: Featured Results in SearchBlox