An X scheduler that counts before it commits
280 characters is the constraint that decides whether a cross-post survives. PostMCP checks it — along with media rules and credit cost — before anything reaches the queue.
Nobody asked for it. We built it anyway. Six weeks later it is the second-most used thing we ship.
Checked at pre-flight. An overrun is reported with the exact excess so you trim the X variant, not every version.
Up to 512MB. Cross-posting the same clip to Bluesky hits its 60-second wall first — reported before you queue.
X API access is priced differently upstream. Every other network costs 1. A post with a link adds 50 once.
The three networks worth mirroring to
You are already writing the hard part. These come nearly free — with the caveats that actually matter.
Almost the same length, so the X version usually needs no rewrite at all. Emoji count as one grapheme, not four bytes.
Room to add the sentence you cut. Publishes as the linked Instagram identity.
A different piece of writing. Worth generating rather than pasting.
X scheduling FAQ
- How do I schedule tweets in advance?
- Write the post, tick the X profiles that should receive it, and pick a date, time and timezone. PostMCP holds it in the queue and publishes at the slot. Until then you can edit it, drag it to another day, force-publish it early or delete it.
- What is the character limit and is it checked?
- 280 characters, and yes — pre-flight reports an overrun before the post enters the queue rather than letting X reject it at publish time. That matters most when the same copy is going to several networks and only X is too tight.
- Why does X cost more credits than other networks?
- Five credits per delivery against one for every other network, because X API access is priced differently upstream. Pre-flight reports the exact cost of a post before you commit, so a multi-network broadcast never surprises your balance.
- Can I post video to X?
- Yes — up to 2 minutes 20 seconds and 512MB. Pass a public video URL as the media and the engine handles the upload. Duration cannot be verified without decoding the file, so the limit is reported to you rather than enforced locally.
- Can I cross-post the same tweet to Bluesky?
- That is one of the most common uses. Bluesky’s 300-grapheme ceiling is close enough to 280 that the same copy usually works unchanged, and both go out from a single action with independent delivery tracking.
- Can an AI assistant post to X for me?
- Yes. PostMCP is a Model Context Protocol server, so Claude, ChatGPT or Cursor can draft, pre-flight and schedule X posts through the same queue — with an approval step before anything publishes.