command.js

var d = document,
    w = window,
    e = w.getSelection,
    k = d.getSelection,
    x = d.selection,
    s = (e ? e() : (k) ? k() : (x ? x.createRange().text : 0)),
    f = 'http://www.tumblr.com/share',
    l = d.location,
    e = encodeURIComponent,
    p = '?v=3&u=' + e(l.href) + '&t=' + e(d.title) + '&s=' + e(s),
    u = f + p;
try {
    if (!/^(.*\.)?tumblr[^.]*$/.test(l.host)) throw (0);
    tstbklt();
} catch (z) {
    a = function () {
        if (!w.open(u, 't', 'toolbar=0,resizable=0,status=1,width=450,height=430')) l.href = u;
    };
    a();
}
void(0)

command.json

{
  "name": "Post to Tumblr",
  "description": "Post the content from the current page to your Tumblr blog.",
  "icon": "https://backtickio.s3.amazonaws.com/icons/tumblr.png",
  "link": "http://tumblr.com"
}