reply_to_inbox
Reply to an existing inbox conversation (DM, comment, or mention) on Instagram, Facebook, LinkedIn, TikTok, YouTube, X, or Threads. You can only reply to conversations that already exist. For a comment or mention, pass message_id (the #id of the comment being answered): comments on one post share a conversation and without it the reply goes under the newest comment on the post. Meta direct-message replies must be within the platform's 24-hour messaging window: a 422 outside_messaging_window means the window has closed, nothing was sent, and the user must answer that DM from the Instagram or Facebook app (mirrored into the inbox) or skip it with mark_inbox_read; do not retry. TikTok replies are comments only, text-only, and capped at 150 characters; they can take a few minutes to appear on TikTok while they pass spam review. YouTube replies are comments only. Threads replies are on the workspace's posts and mentions; a 401 reauth_required means the Threads connection must be reconnected to grant the reply permission. X replies are DM-only and use credits from the organisation's existing balance (X's API fee passed through); a 402 insufficient_credits error means that balance is too low — tell the user and do not retry. attachment_url/attachment_type let you send media on a Facebook or Instagram DM (text is optional when an attachment is set); other platforms are text-only. Set include_next: true to get the next conversation that needs an answer back in the same call (same as get_next_unanswered), so the inbox can be worked through as: get_next_unanswered → draft → reply_to_inbox(include_next) → draft → repeat. A 409 duplicate_reply means this exact reply already went out to this conversation in the last 10 minutes (an earlier call that looked slow or failed did succeed) or is being sent right now: nothing was sent again, do NOT retry it — continue with get_next_unanswered. A 422 reply_not_allowed means the platform refuses replies to this item for good (Facebook #1705: the comment sits on a share or boosted copy of the post, or the commenter restricts replies; YouTube: the thread's canReply is false because comments are off on the video or the comment was removed or held for review): the item is dropped from get_next_unanswered automatically, tell the user, and do NOT retry.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| text | No | The reply text (max 2000 characters; TikTok comments max 150). Optional when attachment_url is set. | |
| message_id | No | For comment/mention threads: the inbox id of the comment you are answering (the 'Message to answer' #id from get_next_unanswered, or a #id from get_inbox_conversation). Every comment on a post shares one conversation, so without it the reply is posted under the newest comment on the post, which can be a different person than the one you drafted for. Always pass it for comments. Ignored for DMs. | |
| include_next | No | After sending, also return the next conversation that needs an answer (full thread + post context), or 'nothing waiting' | |
| attachment_url | No | Media URL to send (Facebook and Instagram DMs only) | |
| attachment_type | No | image, video, audio, or file — required if attachment_url is set | |
| conversation_id | Yes | The conversation ID to reply to |