Post to Lemmy from Codex

Codex drafts it. You approve it. PostDelegate posts it.Lemmy: Posts to one or more communities on your instance.

How to post to Lemmy from Codex

Add PostDelegate to Codex. Add the server to ~/.codex/config.toml as below. Run codex mcp login postdelegate and sign in in your browser.
~/.codex/config.toml
```
[mcp_servers.postdelegate]
url = "https://app.postdelegate.com/mcp-oauth-dynamic"
```
Connect Lemmy in PostDelegate. On the calendar page choose Add Channel, then Lemmy. Enter the instance address starting with http:// or https://, your username or email, and your password. PostDelegate signs in to the instance and shows your account on the channel.
Ask Codex for a draft. Describe the post in plain words. Codex checks your Lemmy channel's rules, creates the post and sends back a preview link.

Teach Codex the posting rules

Add PostDelegate’s AGENTS.md to your repository, so Codex knows the MCP tools, the REST API and the safety rules when it works there. Agent files has the steps.

What to ask Codex

Mention any Lemmy setting in plain words and Codex fills it in. Codex can also read text files in your project, such as a changelog or a draft in Markdown.

Draft a Lemmy post for the selfhosted community with the title “We open-sourced our scheduler” and a link to the repository.
Post the same announcement to two communities, each with its own title, as drafts.
Write a Lemmy post from the project’s README introduction, link to the docs, and save it as a draft.

What Codex can do on your Lemmy channel

Check the rules first. Before writing, it reads your Lemmy channel's length limit (10,000 characters) and required settings.
Draft, schedule or post. It creates a draft, a scheduled post or an immediate post, and runs the same checks as the app.
Use your media. It attaches files from your media library or adds one from a public link.
Review and fix. It lists what is scheduled, changes the Lemmy settings of a post that has not gone out, and deletes posts you no longer want.

Lemmy is made of separate instances, so PostDelegate asks which one you use, for example https://lemmy.world, along with your username or email and password. Each post goes to one or more communities, and every community needs its own title.

Lemmy settings Codex can fill in

Setting	Notes
Community	Required. Choose one or more communities. Each one needs its own title.
Title	Required, at least 2 characters, one per community.
URL	Optional link to attach to the post.

Before you start

Lemmy has no app passwords, so you connect with your real account password. It is encrypted before it is stored.
A post fails with a readable reason if your account is banned, the community no longer exists, or the instance blocks a link in the post.

The Lemmy channel guide has every field, and MCP tools lists exactly what an assistant can and cannot do.

Questions

Will Codex publish to Lemmy without asking me?

Not unless you ask it to. Ask for a draft and the post waits on your calendar until you schedule it, and your workspace's approvals apply as usual. Tools that change data are marked as such, so Codex can ask you before it schedules or deletes anything.

Do I need an API key to connect Codex?

No. Codex signs in with your PostDelegate account through your browser. An API key is only for clients that cannot sign in, as described in MCP clients.

Does it cost extra to use Codex with PostDelegate?

No. The MCP server is on every plan, and Codex runs on your own Codex account, so PostDelegate never charges for AI. Every plan starts with a 7-day free trial with no card.

Can Codex attach images or video to a Lemmy post?

It can use files already in your media library, or add one from a public link. It cannot fetch files from your computer, so upload those in the app first. See MCP tools.

Can I post to several Lemmy communities at once?

Yes. Choose one or more communities in the Community setting. Each community needs its own title, so the same post can be titled differently for each one.

Is my Lemmy password stored?

Lemmy has no app passwords, so you connect with your real account password. It is encrypted before it is stored, and you can change it later with Update Credentials in the channel's menu.

Lemmy from other assistants

Other networks from Codex

Prefer to plan Lemmy posts yourself? See the Lemmy scheduler.