Schedule a note to any combination of Substack, LinkedIn, X, Bluesky, Threads, Instagram, Facebook, TikTok, and Pinterest; Instagram, TikTok, and Pinterest require an image or video. Creates a note draft when draftId is absent. Character limits: Bluesky 300, Threads 500, LinkedIn 3000, X 25000 (posted as a thread). Explicit platformVersions must fit their limits; otherwise overlong platform text is shortened at a sentence boundary, with adjustedPlatforms and warnings returned. When a writer has several connected accounts on Threads, Facebook, TikTok, Pinterest or X, the Note goes to the default account unless socialAccountIds names one from list_social_accounts; with several and no default the request is refused until one is named. Authorized team routing uses workspace and writer. Substack Notes publish from the verified connected profile, not a publication page. Safe to retry: pass a new clientRequestId for each note and reuse it when retrying that note, and a repeat returns the original result instead of scheduling again. Even without one, a note with the same text, platform and time as one scheduled in the last 24 hours is not copied: the result has duplicate: true and the existing schedule ids. To quote a Substack Note or post (like "Restack with a note"), pass its link as quoteUrl rather than in content. To schedule several notes, prefer schedule_notes.