Creating the OAuth app and connecting a blog: Tumblr provider guide.
Settings Schema
Every field is optional, so the settings object can be __type alone:
Fields
tags is a plain string here, not an array. Tumblr takes a comma-separated string, which is
what PostQueen passes straight through. This differs from the top-level tags array on the post
body, which is PostQueen’s own labelling and unrelated to Tumblr’s.
Up to 30 images, or exactly one video. A video cannot be mixed with images.
Content over roughly 4,000 characters is split into several Tumblr text blocks on the way out,
divided on blank lines. That is Tumblr’s own limit for one block; the post still reads as one
piece. Alt text set on an image is carried through.
The post’s character ceiling is 32,768.