This clearly isn't the whole truth given tumbler has a large banner asking you to download the app when you surf to the website.
By definition I cannot provide the entire truth because only a slice of reality is available to me.
As such, the only "not contradictory" response to "is this entire truth" is no. Ergo you are correct.
It's not a partial truth in a tautological way. I'm saying something meaningful - please assume good faith and engage in good faith.