Sickle
Download for macOS

13 October 20263 min readmcpcodex

Connect Codex to your email

Add Sickle to OpenAI Codex — the CLI, the IDE extension or the desktop app — so it can search, read and tidy every mailbox you own.

Sickle is a remote MCP server: Codex talks to it over HTTP, so there is no package to install and no local process to keep running. Sign-in is OAuth, so there is no API key to export either. Once connected, Codex sees every mailbox in your Sickle account at once — Gmail, Outlook, iCloud, Fastmail, Yahoo and any IMAP host.

The Codex CLI, the IDE extension and the desktop app share one configuration file, so adding Sickle in one adds it to all three.

Before you start

  • A Sickle account with at least one mailbox connected. If you do not have one yet, start a free trial and add your mailboxes in the Mac app or on the Mailboxes page. There is a step-by-step guide for Gmail, Outlook, iCloud, Fastmail and any other IMAP mailbox.
  • Codex installed and signed in. Older releases needed an experimental flag for OAuth servers; update Codex if the steps below do not open a browser.

Add the server

Run this in any terminal:

bash
codex mcp add sickle --url https://mcp.sickle.app

Or add it to ~/.codex/config.toml by hand:

~/.codex/config.tomltoml
[mcp_servers.sickle]
url = "https://mcp.sickle.app"

In the desktop app

Open Settings and go to Plugins under Integrations. Switch to the MCPs tab, open the Add menu and choose Add MCP server. Name it sickle, pick Streamable HTTP, paste https://mcp.sickle.app and save.

Codex desktop app settings on the Plugins page, MCPs tab, with the Add menu open showing Add MCP server.

In the IDE extension

Open the gear menu, choose MCP servers and then Add server, and fill it in the same way. Restart the extension when it asks.

Sign in and approve access

codex mcp add starts the sign-in straight away. If no browser opened, run:

bash
codex mcp login sickle

In the desktop app, click Authenticate next to Sickle instead.

Your browser opens a Sickle sign-in page. Sign in and approve the permissions Codex asks for:

  • email_read lets it list your mailboxes and folders, search and read messages.
  • email_change lets it mark messages as read, move them between folders and move them to Trash.

You may also see email_send. Nothing uses it yet: Sickle has no tool that sends mail.

Check it works

bash
codex mcp list

Sickle should be listed and enabled. Inside a Codex session, /mcp shows the same list along with Sickle's tools.

Then ask Codex:

text
Which mailboxes can you see?

It calls list_accounts and names every mailbox in your Sickle account.

Troubleshooting

  • No browser window opened. Run codex mcp login sickle. If that fails, update Codex: OAuth for remote servers arrived in later releases.
  • Codex doesn't list Sickle's tools. Run codex mcp get sickle to check the URL, and that the server is not disabled with enabled = false.
  • Codex only sees some of your mailboxes. It sees exactly the mailboxes in your Sickle account. Add the others in the Mac app or on the Mailboxes page.

Disconnect

bash
codex mcp logout sickle
codex mcp remove sickle

To cut access from the Sickle side, revoke Codex on the Connect AI page in your dashboard; access it already holds ends within the hour.