Platforms and limits
Which platforms we post to and the character limit the agent writes to on each.
Five platforms are supported today. Each has its own rules, and the agent respects all of them at once for whichever accounts an agent posts to.
At a glance
| Platform | Post length | First comment | Images | Notes |
|---|---|---|---|---|
| 3,000 characters | Yes — up to 1,250 characters | Optional | Personal profiles and company pages. The platform PostAgent is built around. | |
| X (Twitter) | 280 characters | No | Optional | Posts are written to fit 280 — an agent posting to LinkedIn and X writes 280-character posts for both. |
| Threads | 500 characters | No | Optional | Connected through the Instagram account it belongs to. |
| 2,200 characters (caption) | Yes — up to 2,200 characters (feed and reels, not stories) | Required | Business or Creator account needed. A post without an image is skipped for Instagram. | |
| 63,206 characters | Yes — up to 8,000 characters (feed and reels, not stories) | Optional | Pages, not personal profiles. |
One post, several platforms
An agent writes one post per slot and publishes it to every account it is attached to. So the length budget is the shortest limit among those accounts: LinkedIn alone gets up to 3,000 characters; LinkedIn + Threads gets 500; anything + X gets 280. If you want long LinkedIn posts and short X posts, run two agents — one per platform — with the same brief. The console's Accounts section shows the limit an agent is writing to and which platform set it.
Images
- Images are on by default per agent and can be turned off in the console. Each post gets one image, drawn from the finished post text in the agent's set style.
- If an image cannot be produced for a slot, the slot is retried on the next poll rather than published bare — an agent with images on never posts without one.
- Instagram will not accept a text-only post. If images are off on an agent that includes Instagram, Instagram is skipped and the post still goes to the other platforms.
First comment
The promo or link you set in the agent's call-to-action goes in the first comment, where it does not compete with the post in the feed. It is posted on LinkedIn, Instagram and Facebook; X and Threads do not support it, so on those platforms the post goes out without it. The console's "Call to action (first comment)" field says, for the accounts that agent is attached to, exactly where the comment will and will not appear — nothing is silently dropped.
Hashtags
The console's "Hashtags" field is a fixed set added on its own line under every post, on every platform. Their length is taken out of the post's character budget up front and the agent is told not to add hashtags of its own, so a post never carries two sets or runs over the limit because of them. Type them any way you like — "tax planning, cpa" is stored as "#TaxPlanning #Cpa". Leave the field blank and the agent decides per post, guided by your brief (which can also say "no hashtags").
Connecting
All connections go through the platform's own sign-in page; PostAgent never sees a password. See Connecting your accounts for the per-platform steps and When an account needs reconnecting for expiry.