How to Connect Multiple Teams Accounts to Codex
Codex ships no Teams connector at all, so reaching your own company’s Teams and a client’s from one session is a question of which MCP server you register, and Carly is the one that holds them both. Authorize each Microsoft identity in Carly, register one server, and a Codex session can search or post in whichever organization you name. Carly holds your Gmail and Outlook mailboxes and every calendar on both sides in the same place.
What one chat can do afterwards
- Search your own company’s Teams and a client’s in the same question.
- Compare threads sitting in two different organizations.
- Post or reply in the tenant you name, not the one that happens to be connected.
- Read channel messages without negotiating an Entra admin consent first.
- Produce a daily brief grouped by organization.
- Answer an escalation that lands at 9pm on Friday, with no session open.
Nothing is merged. Each organization keeps its own authorization, and every tenant stays individually addressable.
Teams here is work and school only
Worth settling before anything else. Microsoft’s personal-account tool surface covers mail, calendar and OneDrive, and Teams is not in it. Everything on this page assumes a work or school identity in a Microsoft 365 tenant, and a second organization means a second tenant with its own administrators.
1. Sort your accounts by tenant
| What you have | Native path in Codex |
|---|---|
| One work Teams account | Only through a server you register |
| A second employer’s or client’s tenant | No connector at all |
| Reading channel messages | Needs ChannelMessage.Read.All, which needs an Entra admin |
| Posting a channel message | Consent-free, oddly, but still needs a server |
| A personal Microsoft account | Not applicable, Teams is work and school only |
| Anything starting when a message arrives | No, nothing watches |
2. Connect each Teams tenant to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Microsoft Teams and click Connect.
- Sign in with the first organization’s Microsoft account and approve access.
- Click Connect again and sign in with the next organization’s account.
- Confirm which tenant each connection landed in before adding the next.
Microsoft silently reuses whichever account your browser already holds, so sign out between accounts or use a separate browser profile. Each tenant approves independently, so one client’s administrators declining does not block the others, and authorization runs in a browser rather than a device-code flow at someone else’s terminal.
3. Register Carly as an MCP server
The CLI route is the shortest:
codex mcp add carly --url https://carlyassistant.com/mcp/Servers added this way land in ~/.codex/config.toml at user scope. The hand-written equivalent:
[mcp_servers.carly]
url = "https://carlyassistant.com/mcp/"
default_tools_approval_mode = "writes"A url key is what makes this a streamable HTTP server; a command key would make it stdio. Codex has no transport field to set, and adding one is a configuration error rather than a hint. Set the approval mode from the start so reads run and anything that posts stops for confirmation.
Then authenticate:
codex mcp login carlySign in to the Carly workspace holding the tenants. Codex supports OAuth and bearer tokens against remote HTTP MCP servers, so no secret sits in a config file. Verify with:
codex mcp list4. Test each tenant read-only
Start a new session so the tools load, then one organization per prompt:
In the Pepsi organization, list the ten most recent messages in the Launch channel with sender and timestamp. Do not post anything.
In the Cisco organization, find the newest thread mentioning the change order and name the channel. Read only.
Then the question a single identity cannot answer:
Search both organizations’ Teams for messages about “change order” from the last 14 days and show the source organization on every row.
If the tools are missing, start a fresh session. Codex loads a newly registered server’s tools at session start, not mid-session.
5. Reuse this routing prompt
Treat Pepsi as Internal and Cisco as Client. Name the source organization on every result. State the target organization before posting anything, and never post in a Client channel without showing me the draft first.
The community server route, and what it costs
For completeness, there is a generic Graph-backed community server, @softeria/ms-365-mcp-server, whose teams preset exposes 65 tools across chats, channels, channel messages, team membership, online meetings, transcripts, recordings, attendance reports and presence. It does support several signed-in accounts, injecting an account parameter into every tool once more than one is logged in. Its README never mentions Codex, so compatibility is an inference rather than a vendor promise.
Three things make it expensive to run.
Organization mode is not retrofittable. Teams tools live behind --org-mode, and the README is blunt about the ordering: “Organization mode must be enabled from the start to access work account features.” Adding it later means redoing the login rather than editing a config line.
Reading a channel needs an administrator; posting to one does not. Checked against Microsoft’s permissions reference, the scopes in that preset do not behave alike:
| Scope | Needs an Entra admin? |
|---|---|
Chat.Read, Chat.ReadWrite, Chat.Create, ChatMessage.Read, ChatMessage.Send | No |
ChannelMessage.Send | No |
ChannelMessage.Read.All | Yes |
ChannelMember.Read.All, TeamMember.Read.All | Yes |
OnlineMeetingTranscript.Read.All, OnlineMeetingRecording.Read.All | Yes |
Presence.Read.All, Channel.Delete.All, ChannelSettings.*.All | Yes |
Read the shape of that. You can send a channel message without an administrator. You cannot read one. That split is a property of Microsoft Graph rather than of any assistant, and it shows up on other hosts’ Teams connectors too. Trimming it with --allowed-scopes only ever narrows what you can do, and --list-permissions is what tells you what sign-in will actually request.
Every tenant is a separate device-code sign-in at your terminal, and one flag quietly undoes the whole point: --expected-username pins the server to one Microsoft account, and the README notes that “pinning collapses the effective MCP mode to single-account: the server does not advertise an account parameter.”
What is still missing: the trigger
MCP servers wait to be asked. The protocol has no scheduler and no event mechanism — its maintainers acknowledge that change detection today means polling — so an MCP connection can answer a question but cannot notice something on its own.
This is the limit no config file fixes. Codex will read, post, reply, react and fetch a recording across two tenants, and it will do none of it until you ask. An @mention landing in a client channel at 9pm starts nothing, and a message nobody thought to tag a bot in is never seen at all. That watching half runs on Carly’s side.
Codex versus Carly on Teams
| Need | Codex alone | Carly MCP server |
|---|---|---|
| Hold two Teams tenants at once | Only via a server you register | Yes |
| Address a specific tenant per call | Depends on the server | Yes, by organization |
| Read and post in channels and chats | Depends on the scopes you got consented | Yes |
| Avoid an Entra admin for channel reads | No | Yes |
| Add a third tenant later | Another device-code sign-in and consent round | A Connect click |
| Act when a message arrives | No trigger | Yes |
| Reach non-Microsoft tools in the same flow | Only by adding more MCP servers | Yes |
Carly runs on the event rather than the request, so the escalation gets answered on Friday evening rather than described on Monday. It authorizes per identity through a browser rather than a device-code flow, which matters when the person who owns the client tenant is not the person editing config.toml, and it reaches roughly 260 apps natively and anything else with a public API through your own key, so Teams is rarely the last step in the chain.
Free Zapier-style workflows; AI agents from $35/month. Connect the tenants at carlyassistant.com/integrations, then point Codex at carlyassistant.com/mcp.
Quick fixes
| Problem | Fix |
|---|---|
| No tools appear after registering the server | Start a new Codex session; tools load at session start |
codex mcp login carly never completes | Finish the browser OAuth flow, then rerun codex mcp list |
| Codex rejected the config | Remove any type key. Codex selects stdio from command and streamable HTTP from url |
| Channel reads fail but posting works | ChannelMessage.Read.All needs admin consent and ChannelMessage.Send does not. That split is Microsoft’s |
| Sign-in bounces to an administrator | Something in the scope set needs consent; each tenant decides separately |
| Both connections landed on the same person | Microsoft reused the live browser session. Sign out between authorizations |
| Codex posts in the wrong organization | Name the tenant in the prompt and require it in every answer |
Frequently asked questions
Can Codex connect to two Microsoft Teams tenants?
Yes, once each identity is authorized in Carly and Codex is pointed at one MCP server. The tenant count is a Carly setting rather than a Codex one, and every answer names the organization it came from.
Do I need an administrator to use Teams from Codex?
For part of it, on the community-server route. Chat tools and sending channel messages need no admin consent, while reading channel messages, reading team or channel membership, and fetching meeting transcripts or recordings all do. Connecting through Carly authorizes each tenant in a browser instead.
Does Teams work with a personal Microsoft account here?
No. The personal-account tool surface covers mail, calendar and OneDrive. Teams is work and school only.
Can Codex watch a Teams channel?
No. MCP servers expose tools that get called during a run, and nothing subscribes to a Teams event. Carly runs on the event, so the 9pm escalation is handled before you open a session.
Related: Multiple SharePoint sites in Codex · Multiple OneDrive accounts in Codex · Multiple Outlook accounts in Codex · Codex MCP servers · Best AI assistants for Microsoft Teams · Microsoft Teams integration
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