@joao_Dubas I understand. I would think you could still get good results with only 128 characters of the description.
I'd truncate the description down to 128 characters before querying, making sure not to include any partial words. Meaning, if you truncate the string to 128 characters, and that would break a word like "product" into "pro", then be sure to drop the entire word.
You could also drop common stop words for your particular language, like "and", "or", "the", etc., since those will be ignored by your language analyzer anyway.