(adj): vs. indirect) -- (straightforward in means or manner or behavior or language or action
(adj): informal or natural; especially caught off guard or unprepared
(adj): vs. studied), uncontrived -- (not by design or artifice; unforced and impromptu
(adj): openly straightforward and direct without reserve or secretiveness
(adj): vs. disingenuous), artless -- (characterized by an inability to mask your feelings; not devious
Probably better than Voltaire's Candida
I knew someone who ran the auto spellchecker on an essay and ended up with a paper on Voltaire's Candid.
Openly straightforward
Citation: I gave them my candid opinion