There is no any website or tool which doing that. I think cipsoft can check how many items is in tibia but I don't think they are doing that. For example they even know how many steps made each character on fire etc. I know that because I wrote an email to cipsoft with a question about my main character when I was doing firewalker achievement. They easily answered me how many steps I did on all floors - underwater/swimming/fire.
We can know how many rare items are in Tibia only by seeing it in public. Sometimes on the websites like TibiaFandom it's written how many of items were made. EXAMPLE
TibiaQA Quick Tour design contestJanuary 06, 2020
TibiaQA Quick Tour Design - resultsFebruary 09, 2020
Character counter to prevent going over the character limit?February 12, 2020
Suggestion - TibiaQa on InstagramFebruary 11, 2020