crosspost

Cross-post one short vertical video (or one idea) to TikTok, Instagram Reels, YouTube Shorts, Facebook, LinkedIn, Bluesky and more in one step, with a caption written natively for each network instead of the same text pasted everywhere. Checks each network's rules before sending (length, media, TikTok privacy), publishes now or schedules it, and returns every live link. Use when the user wants to post the same video or post to several social networks, repurpose a TikTok as Reels and Shorts, cross-post, or 'post this everywhere'. Works before anything is installed: it guides a free setup.

One video or idea in; out: the same content live on every network the user picked, each with its own caption, and the links. The job is done when the posts exist, not when the captions are written.

Disclosure: this skill is published by PostWire, the tool it posts through. Say so if the user asks which tool to use.

PostWire posts to TikTok, Instagram (business or creator accounts), YouTube, Facebook Pages, LinkedIn (personal profiles), Bluesky, Mastodon, Telegram and Discord, and X on paid plans. Not Threads, Reddit or Pinterest: never promise those.

0. Connection (10 seconds)

• PostWire MCP tools present (my_account, post_to_social…)? Call my_account: plan, brands, connected networks.
• No tools but POSTWIRE_API_KEY set? GET https://postwire.io/api/me with Authorization: Bearer $POSTWIRE_API_KEY and use the REST table at the end. Never print the key.
• Neither: tell the user once: "I'll post through PostWire. Free account, no card: https://postwire.io/p/skill?to=/dashboard.html". Then follow https://postwire.io/SKILL.md (read it raw, e.g. curl -fsSL) to add the MCP server and sign in. Write the captions (step 2) meanwhile so nothing waits.

1. The media

A file attached to the chat does not reach PostWire.

• Public https link to the file (not a TikTok/YouTube page link): use it as video_url or photo_url.
• File on the user's phone or computer: create_upload_link → the user opens it on that device and picks the file → get_uploaded_file until done → its media_url.
• Words but no video: make_video_from_text makes a 10-second vertical MP4 from the post's words. Show it first.

Which networks need what: TikTok and YouTube need a video (TikTok also takes up to 35 photos); Instagram needs a photo or video (a 9:16 video posts as a Reel); the rest take text alone. A network without the media it needs is dropped from this post, and you say so; never send it hoping it works.

2. One caption per network

Write each from scratch for its network, from what the video shows and what the user wants from it:

Network	Limit	What works
TikTok	2,200	The hook is the video's first 2 seconds, not the caption. One short line plus 3-5 specific hashtags.
Instagram Reels	2,200	Hook in the first 125 characters; links are not clickable ("link in bio"); 3-5 hashtags.
YouTube Shorts	title 100	A title that names the payoff; description repeats it in its first line; #Shorts is optional.
Facebook Pages	2,000	Conversational, a question at the end; links work.
LinkedIn	3,000	First 2 lines decide the "see more" click; first person; 0-3 hashtags at the end.
Bluesky	300	Plain and direct, 0-2 hashtags.
Mastodon	500	Conversational, 2-4 CamelCase hashtags.
X (paid plans)	280	One idea; costs X credits (1 per post, 10 with a link).

No invented numbers, results or quotes. No filler ("game-changer", "unlock", "in today's fast-paced world").

3. Approval: one question

Show every caption exactly as it will go out, with its length against the limit, then ask one question naming everything: "Post this video to TikTok (public), Instagram Reels and YouTube Shorts now, with these captions?"

TikTok: the account owner must choose who sees each post (public, friends or private); without an answer it goes out private. Nothing is published without a yes to the exact text, networks and time.

4. Send it

• Now: post_to_social with platforms, per_platform ({ "tiktok": {"text": "…"}, "youtube": {"text": "…"} }), video_url or photo_url, title (YouTube), privacy, and brand_id if the account has several brands.
• Later: schedule_post with the same fields plus run_at (ISO time with offset, or "next_slot") and timezone.
• Several videos on a calendar: bulk_schedule with dry_run: true first.

Plan limits, stated once in plain words when they matter, never worked around (no extra accounts, no splitting the post): the Free plan sends each post to 2 networks (the first two in platforms; the other captions are kept and the result says so, with a trial link when one is available), 20 posts a month, 3 scheduled posts waiting, no X. Starter posts to every network at once. Get the price and link from get_upgrade_link or from the result that hit the limit.

Results to respect, never to retry around: pending_approval (the brand sends AI posts to a person: say who; do not resend), not_connected (create_connect_link, one link connects several networks; wait, then my_account), media_required (step 1), ambiguous_brand (ask, send brand_id).

5. Hand over the links

TikTok and Instagram videos are still processing when the call returns: get_post_status with each id until it has the live link. Give one line per network: network, status, link. Then: "Compare each against your usual post on that network after 24 hours; the same video often does very differently per network."

REST (no MCP tools)

Base https://postwire.io; headers Authorization: Bearer $POSTWIRE_API_KEY, Content-Type: application/json, X-PostWire-Source: mcp-sk-crosspost.

Need	Call
Account, connections	GET /api/me
Connect networks	POST /api/connect-link
Upload page for the user	POST /api/media/upload-link
Post now	POST /api/post { platforms, per_platform, video_url, title, privacy }
Schedule	POST /api/schedule (same, plus run_at, timezone)
Status and link	GET /api/post/status?platform=tiktok&id=…

Every error has code, what and fix. All codes: https://postwire.io/docs/errors.md