How to post to Instagram from Codex

The short answer

1. Paste ReelGenie’s setup prompt into Codex and follow it.
2. Create a token on ReelGenie’s Agents page and give it to Codex privately.
3. Connect your Instagram professional account in ReelGenie.
4. Codex makes the slides, or takes your finished Reel, and uploads the exact files.
5. Choose feed, Reel or Story, then approve the account and time.
6. Check the result: published, or failed with Instagram’s reason.

Can Codex post to Instagram?

Not by itself. Codex has no Instagram login, and Instagram only lets approved apps publish, and only to professional accounts. Connected to ReelGenie, Codex can: it hands ReelGenie the finished files and caption, and ReelGenie publishes them through Instagram’s own publishing API after you approve. You don’t need a Meta developer app or a script of your own.

1. Connect Codex to ReelGenie

Create a free ReelGenie account first. Then copy the setup prompt from the Codex setup page into Codex. It installs the ReelGenie skill and walks you through the connection one step at a time. A ReelGenie plugin for Codex isn’t listed yet; until it is, this prompt and a token are the way in.

Codex connects with a revocable token. A team admin creates it on ReelGenie’s Agents page for the workspace you want, and you choose there whether Codex may approve deliveries itself. Keep the token out of the chat: Codex reads it from an environment variable.

codex mcp add reelgenie --url https://reelgenie.app/api/mcp --bearer-token-env-var REELGENIE_MCP_TOKEN

Check that the ReelGenie connection works and list my workspaces and connected social accounts.

2. Connect your Instagram account

Codex can’t sign in to Instagram for you. Open ReelGenie’s Accounts page, choose Instagram and sign in there. Instagram only lets apps publish to professional accounts, so switch a personal account to a creator or business account in the Instagram app first. It’s free.

3. Make the post in Codex

Agree on the idea before any images are made. Codex reads your workspace’s brand brief and proposes angles.

Suggest three Instagram carousel ideas for [topic] that fit my brand brief. Give the cover line and what the first slide shows for each. Wait for me to choose before making images.

Codex makes the slides with its image tool, or lays out text slides through ReelGenie’s slide tool. Ask for the cover and one inside slide first, and check the spelling on both before it makes the rest.

Make the cover and slide 2 as 1080 × 1350 JPEGs in my brand colours. Show me both before making the rest.

Reels, carousels and single images: what Instagram accepts

• Carousel: 2 to 20 images. 1080 × 1350 portrait takes up the most room in the feed. Keep every slide the same size, because Instagram shows them all in one frame.
• Single image: one photo or graphic in the feed, same sizes as a carousel slide.
• Image files: JPEG, each up to 8 MB and 12 MB in total. ReelGenie warns before approval if a PNG or WebP image could be refused, so ask Codex to save JPEGs.
• Reel: a finished vertical 9:16 MP4, for example 1080 × 1920, up to 500 MB. Codex doesn’t make video itself; bring one from your editor or a video tool.
• Story: one image or one video, shown for 24 hours.

4. Upload and preview the exact files

Codex uploads each file straight from your computer. ReelGenie checks each one’s size, format, pixel dimensions and fingerprint, in order, so the preview is the file Instagram receives.

Save these slides in order with the caption and hashtags as a private ReelGenie post and open it for review. Don’t send anything yet.

If your Codex has a built-in browser, it can open the review page beside the conversation. If one slide is wrong, Codex can replace just that image while the post is still in review.

5. Choose placement and approve

Instagram options you can set before approval:

• Feed or Story: a Story is one image or one video. A video in the feed goes out as a Reel.
• Reels: the cover frame, and whether it also shows in your feed.
• Alt text and people tags for each image.
• Collaborators: up to 3 accounts.

Then tell Codex the account and the time. Codex repeats those details back before anything is approved, so you approve every post before it goes live. If the token doesn’t allow Codex to approve, you approve in ReelGenie instead.

Schedule this carousel to my Instagram feed for Tuesday at 8:00 Sydney time, with alt text for each slide. Confirm the details with me first.

Before approval, ReelGenie checks the delivery: it test-reads the files Instagram will fetch, and warns you if the Instagram sign-in won’t last until the scheduled time.

6. Check whether it actually posted

Scheduled isn’t posted. Each account shows its own result:

• Scheduled: delivery is planned and nothing has been sent yet.
• Published: Instagram reports the post as live.
• Failed: Instagram’s reason is shown in plain words, so you know what to fix.

Did my Instagram post publish? If anything failed, tell me why and what to do.

After 24 hours Codex can read the post’s views and likes against your account’s usual results. Treat that as how this post did compared with your own recent posts, not as proof of growth.

What Codex can’t do here

• It can’t sign in to your Instagram account. You do that on ReelGenie’s Accounts page.
• It can’t create its own token. A team admin does that on the Agents page.
• It won’t send anything you haven’t approved: the post, the account, the placement and the time.
• It can’t publish to a personal Instagram account. Instagram only allows professional accounts.

The free plan covers 30 posts a month across your team, 1 brand and 3 connected accounts. A post sent to several accounts counts once. Solo is US$19/month for unlimited posts. Compare plans.