The Marvel Cinematic Universe Wiki's canon policy is pretty simple: every movie, one-shot, and TV series is canon. Every tie-in material (comic books, books, video-games) is canon unless it contradicts the established continuity of the movies and the TV series.
Therefore, to ensure the most comprehensive way of collecting all information, the canonicity of material is evaluated only regarding what is explained in this policy.
Marvel Cinematic Universe Canon
The Marvel Cinematic Universe Wiki considers as canon every material regarding to the films, Marvel One-Shots and TV series that belong to the Marvel Cinematic Universe, either what is stated and confirmed on-screen, or what is confirmed off-screen by the Marvel staff and crew members (directors, writers, producers, showrunners). The latter includes, but is not limited to, interviews, audio commentaries, and DVD features.
Comics, books and video games developed set within Marvel Cinematic Universe are also considered canon, being the only exception that a particular comic or video game contradicts the information presented in a movie or TV series. In that case, that particular comic or video game is considered non-canon.