How to post to X (Twitter) from Codex CLI
Codex CLI finishes the task, then writes the post about it. On X that means 280 characters and no URL.
How do I post to X from Codex CLI?
Add the planpo.st MCP server to Codex CLI, connect X once in the dashboard, then ask. The first three steps are one-time.
- 1
Create an API key and add planpo.st to Codex CLI
Make a scoped key in planpo.st under Settings. Add a [mcp_servers.planpost] table to ~/.codex/config.toml, or run codex mcp add and answer the prompts. The hosted form reads the token from the environment variable named in bearer_token_env_var, so export PLANPOST_API_KEY in your shell first.
- 2
Confirm the server is connected
Start Codex and run /mcp to check that planpost is connected.
- 3
Connect X
Connect the X account in the planpo.st dashboard under Connections. OAuth needs a person at a browser, so the agent cannot do this part alone; it can call get_connection_link and hand you the URL to open.
- 4
Know what the post needs
An X post needs text of 280 characters or fewer with no URL in it. That includes bare domains such as example.com, which X turns into links by itself. Nothing in platformSettings is required.
- 5
Ask in your terminal
Say what to post and when. Codex CLI finds the X connection, creates the post, and tells you whether it was scheduled or kept as a draft, with the reason.
[mcp_servers.planpost]
url = "https://mcp.planpo.st/mcp"
bearer_token_env_var = "PLANPOST_API_KEY"[mcp_servers.planpost]
command = "npx"
args = ["-y", "planpost-mcp"]
[mcp_servers.planpost.env]
PLANPOST_API_KEY = "pk_live_xxx"Config location: ~/.codex/config.toml, or .codex/config.toml in a trusted project. Replace pk_live_xxx with your own key.
Hosted or local for Codex CLI?
For Codex CLI I would use hosted with bearer_token_env_var, since the config file then holds no secret and can be shared. Use local when you would sooner keep the key in the config file's env table than in your shell profile.
- The hosted form reads the token from an environment variable rather than the file, so export PLANPOST_API_KEY in your shell.
- `codex mcp add` does the same thing interactively if you would rather not edit TOML.
The full walkthrough is on the Codex CLI setup page.
What can Codex CLI do on X?
It can schedule single posts and threads, reply to or quote an existing post, and keep a separate X version of a post that also goes to other networks. It cannot attach media or include a link.
Single post
280Text up to 280 characters. If the shared text is longer, put a shorter cut in platformContent.twitter and the other networks keep the long one.
Thread
2 to 25postType "thread" with threadSegments, each segment 1 to 280 characters. A thread post can target X and nothing else, so the other networks get their own post.
Reply or quote
platformSettings.twitter.replyToId publishes the post as a reply to that post ID, quoteTweetId as a quote of it.
Not available
limitsImages, video, polls and links. Attachments on a post that targets X are left out of the X version and the text goes out alone.
There is nothing to upload for X, since posts go out as text. When the same post also targets a network that takes images, Codex CLI sets platformMedia so the picture goes there and X gets the words.
Which settings does a X post take?
X has two optional settings and no required ones. Most of what shapes an X post sits outside platformSettings, in the post type and the per-network text, so those rows are listed too.
| Field | Allowed values | If you leave it out | Worth knowing |
|---|---|---|---|
| platformContent.twitter | Text, 280 characters or fewer, no URL | The shared content | Over 280 here is rejected with a 400. If the shared content is over 280 and this is absent, the post is saved as a draft with char_limit. |
| postType | "post" or "thread" | "post" | "thread" with any network other than X in connectionIds returns 400: Thread can only publish to X (Twitter). |
| threadSegments | 2 to 25 strings, each 1 to 280 characters | None | Required when postType is "thread". Fewer than 2 segments or a segment over 280 returns 400. |
| platformSettings.twitter.replyToId | ID of the post to reply to | Not a reply | Ignored for threads, which chain their own replies. |
| platformSettings.twitter.quoteTweetId | ID of the post to quote | Not a quote | Sent as quote_tweet_id on a single post. |
| media, platformMedia.twitter | Not used | Text only | Attachments are skipped at publish. The post still goes out, without them. |
What do I type to post to X from Codex CLI?
Plain requests work. Each example lists the tool calls Codex CLI makes in response.
1. One post, no link
You say
Read the pull requests merged this week. Write one post about the most interesting part and schedule it on X for tomorrow 09:00 Europe/Warsaw. Keep every URL and domain name out of it.
Tool calls
list_connections()
create_post({ content: "<240 characters, no URL>", connectionIds: ["<x id>"], schedule: "tomorrow 09:00 Europe/Warsaw" })One scheduled post. If a link slips into the text, create_post saves it as a draft and returns link_in_x_post with the offending URL, so the fix is a rewrite and an update_post.
2. A thread
You say
Open RELEASE_NOTES.md. Turn it into a five-post thread for X, one point per post, and schedule it for Thursday 17:00.
Tool calls
create_post({ content: "<first segment>", postType: "thread", threadSegments: ["<1>", "<2>", "<3>", "<4>", "<5>"], connectionIds: ["<x id>"], schedule: "thursday 17:00" })A thread of five posts, each checked against 280 characters when it is created. The segments publish in order as replies to the one before.
3. Link on the other networks, clean cut on X
You say
Use the notes in TODO.md under Done. Post it to LinkedIn, Threads and X at 10:00 tomorrow. LinkedIn and Threads get the link, X gets a version without it.
Tool calls
create_post({ content: "<text with https://...>", platformContent: { twitter: "<same idea, no URL>" }, connectionIds: ["<linkedin id>", "<threads id>", "<x id>"], schedule: "tomorrow 10:00" })
preview_post({ id: "<post id>" })One post, three networks. preview_post shows the text each one receives and its character count, so you can see the X version is link-free before the slot arrives.
What stops a X post from Codex CLI?
The tag on a card is the code that comes back in the tool result.
No links, anywhere
link_in_x_postThe X API bills a post with a URL at $0.20 and one without at $0.015, and every thread segment is billed as its own post. planpo.st rejects links in anything it sends to X instead of passing a 13 times surcharge on.
Bare domains count
X links example.com with no https in front, so the check catches it too. Writing "planpo.st" in an X post trips it.
280 characters per post
char_limitCounted on the text X receives: platformContent.twitter when it is set, the shared content when it is not. Threads are checked per segment.
Text only
Images and video are not attached to X posts today. The post publishes without them and the other networks on the same post keep theirs.
A thread is its own post
A thread cannot share a post with LinkedIn or Threads. Create the thread for X, then a second post for the rest.
A thread can stop halfway
If a segment fails, the ones before it are already live. The result is marked failed and lists the IDs that did publish.
The token comes from your shell
Codex CLIThe hosted config names an environment variable, it does not hold the key. If PLANPOST_API_KEY is not exported in the shell that starts Codex, every call fails with an authorization error.
Can Codex CLI tell me what a X post earned?
On X, mostly no, and I would sooner say so. Revenue is matched to a post through the tracked link in it, and planpo.st sends no links to X, so an X post has no click to match a payment to. get_revenue_overview still returns your totals and recent transactions. The practical setup is to let the same idea carry its tracked link on LinkedIn or Threads, where links are clickable, and read the per-post numbers there.
Codex CLI and X: questions people ask
- Can Codex CLI attach an image to an X post?
- No. planpo.st publishes X posts as text only today. An attachment on a post that targets X is left out of the X version, and the other networks on the same post still receive it.
- Why does planpo.st reject links in X posts?
- Cost. The X API charges $0.20 for a post that contains a URL and $0.015 for one that does not. Each reply and each thread segment is billed the same way, so moving the link into a reply only adds a request. The API returns the reason and the URL it found.
- How long can a thread be?
- 2 to 25 segments, each 1 to 280 characters. A thread post targets X only.
- What happens when Codex CLI sends a X post that breaks a rule?
- It is told at once. The usual case on X is a URL in the X copy: the post is kept as a draft and the tool result carries link_in_x_post plus the fix, which Codex CLI applies with update_post.
- Where does the config go?
- In ~/.codex/config.toml, or .codex/config.toml in a trusted project. It is TOML, not JSON, which trips people who paste a snippet from another client. Once it loads, the X tools are available in every session.
- Does the key have to be in the file?
- Not for the hosted server. bearer_token_env_var names a variable and Codex reads the key from your environment, so the file can be shared. The local form puts it under [mcp_servers.planpost.env]. Neither choice changes what you can post to X.
Keep going
X from other agents
Other networks from Codex CLI