Alt text, video covers, separate edits and X long posts
Fields on the existing post create and update calls for alt text, video covers, separate edits and X long posts.
These are fields on the existing post endpoints (POST /api/v1/posts, PATCH /api/v1/posts/{id}), the create_scheduled_post and update_scheduled_post tools, and sociahive posts create|update. There is no new endpoint.
Every field is on every plan. X long posts also need an X Premium subscription on the account, and posting to X is on paid plans.
Alt text
alt_text on an image in media[] (up to 1,000 characters). Sent to Instagram, Facebook, LinkedIn, Threads, Pinterest, X and Bluesky; other platforms do not take it.
- Agent:
altTexton each media item. - CLI:
--alt "<text>", once per image, in order.
Video cover
On a video in media[]:
| Field | Meaning |
|---|---|
cover_url | An image to use as the cover (an upload or a grabbed frame). Sent to YouTube, Instagram reels and Pinterest. |
cover_time_ms | The frame time in milliseconds. Sent to Instagram reels (when there is no cover_url) and TikTok. |
Facebook, LinkedIn, X, Threads and Bluesky take no cover; the platform keeps its own.
- Agent:
coverUrl/coverTimeMson each media item. - CLI:
--video-cover <url|ms>, once per video, in order.
Edit one platform separately
platform_overrides.<platform>.detached: true keeps that platform's own text and media; it no longer follows edits to the shared content. Remove it to re-attach. Not offered on X Articles or reminder posts.
- Agent:
detachedPlatforms: ["twitter"]. - CLI:
--detached twitter(repeatable).
X long posts
An X account with X Basic, Premium or Premium+ may post up to 4,000 characters as one post. Each account's limit is text_limit in GET /api/v1/connected-accounts (and in list_accounts). A post longer than the account's limit is refused when it is scheduled, never at publish. If X refuses a long post, the error is X_LONG_POST_REFUSED and the account's subscription is read again.
Related
- Signatures:
platform_overrides.<platform>.signature_id. - Posting slots:
nextSlotand--next-slot. - Short links: links in a post become
/l/<code>at publish.