That is so far from being called as a tool, it is just a Twitter account for certain altcoins price. Knowing the fact that there are already so many people out there doing the same thing like this, you probably need to find a new idea.
At first, by reading the title of the topic I thought this is some kind of a chrome extension or something. Turns out, it's not.
Indeed, it's just a twitter account which is maybe a bot.
Moreover, a twitter account isn't really helpful to notify about altcoins due to many accounts (following or followers) which update every second, you can't get notified unless always check the last tweet of a twitter account. In this case, better to visit coinmarketcap and watch over a specific coin that you want.