Which ChatGPT plans can post via MCP?

The confirmation modal changes what MCP is good for

Even on a plan that supports it, an MCP write action in ChatGPT is not a background job. Before the tool runs, ChatGPT shows you the tool name and the arguments and waits for you to approve. That is the right default for a client that can be steered by whatever text it just read, and it is worth understanding before you design around it.

The practical consequence: MCP in ChatGPT is excellent for drafting and publishing while you are sitting there, and unsuitable for anything that has to happen at 9am on a Tuesday whether or not you are at a keyboard. If your workflow is the second kind, do not fight the modal. Have the agent schedule instead of publish, so the approval happens now and the post goes out later on its own.

If you are on Plus or Free: two routes that work

1. A Custom GPT with an Action

Actions are OpenAPI-described HTTP calls, they predate MCP support in ChatGPT, and they are available on Plus. You describe one endpoint, set the auth header, and the GPT can call it. This is the answer for the largest group of people asking this question.

openapi: 3.1.0
info: { title: OpenTweet, version: "1.0.0" }
servers: [{ url: https://opentweet.io }]
paths:
  /api/v1/posts:
    post:
      operationId: createPost
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                text: { type: string }
                publish_now: { type: boolean }
                scheduled_date: { type: string, format: date-time }
              required: [text]
      responses: { "200": { description: Created } }

Set the Action auth to API Key, header name Authorization, value Bearer ot_your_key. Step by step with screenshots is in make a Custom GPT post to Twitter.

2. An automation that calls the endpoint

If you want posts to go out on a schedule with no ChatGPT session involved at all, skip the chat client. A cron, a workflow tool, or a few lines in your own service can hit the same endpoint directly, and nothing has to be approved in a modal.

curl -X POST https://opentweet.io/api/v1/posts \
  -H "Authorization: Bearer ot_your_key" \
  -H "Content-Type: application/json" \
  -d '{"text":"Weekly changelog is up.","scheduled_date":"2026-09-02T09:00:00Z"}'

More on the general shape of that choice in API vs MCP for posting, and the walkthrough is in post to Twitter from ChatGPT.