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+Codex + Tesselith

How to connect Codex to Tesselith

Connect OpenAI Codex to Tesselith and schedule social posts from the Codex CLI or the Codex IDE extension. Codex talks to Tesselith’s MCP server, so it can draft, queue and schedule posts on every channel you’ve connected. Keep a human in the loop: publishing now and deleting always ask for your confirmation.

Join the waitlistMCP docs

What do I need before connecting?

You need the Codex CLI or IDE extension and a Tesselith workspace on Pro, Team or Agency (every new workspace starts with a 14-day Pro trial) with at least one channel connected. The CLI, the IDE extension and the ChatGPT desktop app share one config file, ~/.codex/config.toml, so you configure Tesselith once.

1 · Connect · a few minutes

Run this

terminal
# 1. Add the Tesselith MCP server
codex mcp add tesselith --url https://api.tesselith.com/mcp

# 2. Sign in through your browser
codex mcp login tesselith

# 3. Check it
codex mcp list

2 · Ask · live in Tesselith

Ask Codex to post for you

Draft a Mastodon thread announcing the changes in this PR.

Used Tesselith · create_draft

Created a three-post Mastodon draft from the PR description, each under 500 characters. It's in Tesselith as a draft with a link to review it.

Also try:

  • “Queue the draft for the next free Mastodon slot.”
  • “List my Tesselith channels and their status.”
  • “What's scheduled for Telegram tomorrow?”

The setup at a glance

  1. Add the server
  2. Sign in
  3. Verify inside Codex
  4. Use it from the IDE extension

One connection, every channel

Connect your accounts in Tesselith once. From then on Codex can plan and schedule for any of them, and Tesselith publishes at the time you set, even after the conversation ends.

  • XSoon
  • Instagram
  • Facebook
  • LinkedInSoon
  • Threads
  • YouTube
  • TikTokSoon
  • DiscordSoon
  • Telegram
  • RedditSoon
  • PinterestSoon
  • Bluesky
  • Mastodon
  • Dev.toSoon
  • HashnodeSoon

How do I connect Codex to Tesselith, step by step?

  1. 1. Add the server

    codex mcp add writes an entry to ~/.codex/config.toml. You can also add it by hand.

    ~/.codex/config.toml
    [mcp_servers.tesselith]
url = "https://api.tesselith.com/mcp"

  2. 2. Sign in

    Run codex mcp login tesselith. A Tesselith window opens. Sign in, pick the workspace, untick anything you don't want the agent to do, and click Allow access. On a remote machine, add --no-browser to get a link you can open elsewhere.

  3. 3. Verify inside Codex

    Start codex and run /mcp to see Tesselith and its tools, then ask Codex to list your channels. Tools load when a session starts, so restart after changing the config.

  4. 4. Use it from the IDE extension

    The Codex IDE extension reads the same config.toml. Restart your editor after adding Tesselith and it's available there too.

Can I use an API key instead of signing in?

For a server or CI job, point Codex at an environment variable holding your key. In Tesselith, open Settings → Developers, create an API key and tick only the scopes the agent needs. Keys start with tsl_live_ and are shown once, so store it in your password manager or a secret store.

~/.codex/config.toml
[mcp_servers.tesselith]
url = "https://api.tesselith.com/mcp"
bearer_token_env_var = "TESSELITH_API_KEY"

# then, in the shell that runs codex:
# export TESSELITH_API_KEY=tsl_live_…

What can Codex do in Tesselith?

The server at https://api.tesselith.com/mcp exposes these tools. Codex only gets the permissions you approve, and never more than your own role.

Tesselith MCP tools available to Codex
What it does
list_channelsLists your connected accounts and their status
list_posts / get_postFinds posts by status or channel, or reads one
get_queueShows a channel's upcoming posts and free slots
suggest_best_timeSuggests the next free slot and your best hours
get_analytics_summaryCounts active channels, drafts and published posts
create_draftDrafts a post for one or more channels
update_postChanges a post's text, channels or media
add_to_queueGives a post the channel's next free slot
schedule_postPins a post to an exact time
upload_media_from_urlAttaches an image or video from a public URL
publish_nowPublishes within a minute, only after you confirm
delete_postDeletes a post, only after you confirm

Why is Codex not working with Tesselith?

Almost every failure is one of these. Tesselith returns a readable error, so asking Codex“what went wrong?” usually points at the right row.

Troubleshooting Codex with Tesselith
Fix
Startup times outRaise startup_timeout_sec = 30 under [mcp_servers.tesselith].
401 with an API keyTESSELITH_API_KEY isn't set in the shell that launched Codex, so the header is empty. Export it and restart.
Browser sign-in can't reach CodexUse codex mcp login tesselith --no-browser on remote machines.
Tools don't show upMCP tools load at session start. Restart Codex after editing config.toml.
An older Codex rejects url =Update Codex. Very old versions needed experimental_use_rmcp_client = true for HTTP servers.
403: your plan doesn't include API accessMCP is included on Pro, Team and Agency. New workspaces get a 14-day Pro trial; upgrade under Settings → Billing.
401: connection revoked or lost accessSomeone disconnected the assistant in Settings → AI assistants, or your role changed. Connect again and approve the workspace.
The assistant can read posts but can't scheduleYou unticked Schedule and queue on the consent screen. Disconnect and connect again, keeping that permission.
No channels foundThe assistant only sees accounts already connected in Tesselith. Connect them under Channels first.
Post scheduled at the wrong timeTell the assistant your time zone. Tesselith takes ISO 8601 times with an offset, and your workspace time zone is shown in get_queue.
429: rate limitedEach connection can make 120 requests a minute on Pro, 300 on Team and 600 on Agency. Wait for the Retry-After seconds.

Codex and Tesselith: frequently asked questions

Does Codex cloud use my Tesselith connection?
Codex cloud doesn't read your local config.toml. Use the CLI or IDE extension, or connect Tesselith to ChatGPT.
Where does Codex store MCP settings?
In ~/.codex/config.toml, shared by the CLI, the IDE extension and the ChatGPT desktop app. Trusted projects can also have .codex/config.toml.
Should I use OAuth or an API key?
Use the browser sign-in on your own machine. Use an API key with limited scopes on servers and in CI.

Codex’s own documentation: OpenAI docs.

Connect other AI agents

ClaudeClaude CodeClaude CoworkChatGPTOpenAI APICursorVS Code (GitHub Copilot)WindsurfZedClineGemini CLIHermes AgentOpenClawGoosen8nMistral Le ChatPerplexityManus

Ready to connect Codex?

Create your Tesselith account, connect your channels, and Codex can start scheduling in minutes.

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