Prompt
Here is my 1,500-word blog post about moving our coffee roastery to a 4-day week. Pull out the single most surprising result and write it as a Threads post under 450 characters, first person, no hashtags. Save it as a draft for Threads.How to do it
- Mint a Threads agent key In https://app.socialhandoff.com, open Connections, connect your Threads account, then create an agent key scoped to Threads with draft permission only. Copy the key when it is shown; only its hash is stored.
- Turn on developer mode In ChatGPT settings, enable developer mode so you can add a custom connector.
- Add the connector Create a connector with the URL https://app.socialhandoff.com/mcp and your Threads key as the bearer token. ChatGPT needs an HTTPS URL it can reach, so use the hosted app or a public self-hosted instance.
- Brainstorm, then draft Talk through angles in the chat. When you pick one, ask ChatGPT to call draft_post for Threads. The post lands in the approval inbox, not on your profile.
Example draft
Six months ago we moved our roastery to a 4-day week. I expected output to drop. It did not. We roast the same volume, and green coffee waste fell because nobody is rushing a Friday batch while tired anymore. The hardest part was not scheduling. It was me learning to stop checking the roaster logs on day 5.
Gotchas
- Keep each Threads post within 500 characters, and remember that Threads counts emoji by their UTF-8 bytes, so a few emoji use more of the limit than they appear to. The per-network length guardrail flags longer drafts before they reach the inbox.
- A draft too long for one post can go out as a reply-chain thread, with each part published as a reply to the one before. Every part has its own 500-character limit, and a carousel of 2 to 20 images or videos can lead the chain.
- Threads allows 250 posts per account in any 24 hours. The quota is checked before each publish, so a post that would go over it is stopped before it is sent rather than failing at the network.
- ChatGPT connectors need a public HTTPS endpoint. A self-hosted instance on localhost will not work; use the hosted app or expose your instance behind TLS.
- Character limit: 500 characters per post. Emoji count as their UTF-8 bytes, so an emoji can use up to 4 characters of the limit.
- Links: Up to 5 links per post. Threads generates a preview for the first one.
- Carousels: 2 to 20 images or videos in one carousel post.
- Image files: JPEG or PNG, up to 8 MB. Threads fetches each file from a URL at publish time.
Frequently asked questions
Which ChatGPT plans can add the connector?
Custom connectors depend on ChatGPT developer mode, which OpenAI controls by plan. If you can add a custom MCP connector, you can connect to https://app.socialhandoff.com/mcp with a bearer key.
What can a Threads post include?
Text up to 500 characters, a single image or video, or a carousel of 2 to 20 items, with alt text on images. A longer idea can go out as a reply-chain thread, and every part waits for approval like any other draft.
What happens if a Threads publish fails?
The post is marked failed with the error, a post.failed webhook fires if you registered one, and you can fix and retry from the inbox.