How to Connect Multiple Slack Workspaces to Claude Cowork
Claude Cowork holds exactly one Slack workspace at a time, and authorizing a second overwrites the first. Connect every workspace to Carly, add Carly to Claude once, and a single Cowork task can search or post in whichever workspace you name. Carly holds your Gmail and Outlook mailboxes and every calendar on both sides in the same place.
One check first, because it takes five minutes and can end the problem. If you reach a client through a Slack Connect channel rather than as a member of their workspace, you are already covered on one connection.
1. Add your Slack workspaces to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Slack, click Connect, and authorize the workspace.
- Click Connect again for the next one, and keep going for as many workspaces as you want.
Each workspace keeps its own authorization, and Carly reaches only the channels that account can already open. If a workspace restricts app installation, a Slack owner or admin approves Carly once.
Carly connects to thousands of apps, so while you are on that page you can add your inboxes, calendars, CRM, and anything else you want Claude Cowork to reach through the same connector.
2. Connect Carly to Claude Cowork
In Claude:
- Open Customize in the sidebar.
- Select Connectors.
- Click +, then Add custom connector.
- Paste
https://carlyassistant.com/mcp/. - Click Add and authorize your Carly account.
- In the Cowork task, open + → Connectors and enable Carly.
Anthropic documents this path in its remote MCP connector guide. Cowork is on paid plans only, and on Team or Enterprise an Owner enables connectors for the organization first.
What the finished setup gives you
With one Carly connector in Cowork, you can:
- search your own, a client’s, and a partner’s Slack in one task;
- get the source workspace named on every row that comes back;
- post in the workspace you name, not the last one authorized;
- pull a status brief from every workspace you belong to;
- keep a scheduled task pointed at the right company;
- match a Slack thread against the email and calendar accounts connected alongside it.
The workspaces stay separate underneath. Carly supplies the routing, and Claude remains where you run the task.
Why the native Slack connector does not solve this
Anthropic documents no way to add a second Slack workspace. The clearest account of the limit comes from users rather than from Anthropic: an open request on Anthropic’s public issue tracker, filed on 6 April 2026 and still active in August, states the built-in Slack connector supports only one workspace per Claude account, with no way to add a second through the UI or configuration. A separate, closed report describes the mechanism, which is that authenticating into one workspace overwrites the other’s token.
Slack Connect is the row that surprises people. Slack documents that channels created in your workspace are hosted and owned by your organization, with up to 250 organizations in a single shared channel. Enterprise Grid does not solve it: Slack documents that workspaces in an Enterprise organization have their own application installations.
| How you reach it | What it actually is | Native path in Cowork |
|---|---|---|
| Your own company Slack | Your workspace | Yes |
| A client channel shared via Slack Connect | A channel in your workspace | Yes, already covered |
| A client workspace you were added to as a member | A second workspace | No |
| A partner or community Slack you joined | A second workspace | No |
| Another workspace in your Enterprise Grid org | A separate installation | No |
Cowork’s Slack connector versus Carly
| Need | Slack connector in Cowork | Carly connector |
|---|---|---|
| Search one workspace deeply | Yes | Yes |
| Send, draft, and preview messages | Yes, in-client | Yes |
| Create channels, canvases, and reactions | Yes | Not all of them |
| Hold several workspaces at once | No, one at a time | Yes |
| Name the source workspace on every answer | No | Yes |
| Start when a Slack message arrives | No | Yes |
Inside one workspace the native connector is deeper, because it is Slack’s own hosted MCP server: previewing a formatted message in the Slack client before it goes, creating and updating canvases, working through reactions and channel membership.
Across workspaces it has nothing to offer, and that is the case this page is about. Carly holds several at once and names the source workspace on every answer, so the wrong-company summary cannot happen quietly. It also fires on the event rather than waiting for the next scheduled sweep. Carly offers free Zapier-style workflows; AI agents start at $35/month.
Quick fixes when a workspace does not appear
| Problem | Fix |
|---|---|
| The second workspace replaced the first | Expected on the native connector. Keep every workspace in Carly instead |
| Cowork answers from the wrong Slack | Check which workspace is bound, and route by name through Carly |
| A client’s channels are missing | Confirm whether you are a member of their workspace or only in a Slack Connect channel |
| Slack authorized the wrong workspace | Slack preselects the last one used, so check the name on the consent screen |
| A scheduled task returns nothing | On the native connector it runs against whatever workspace is bound now |
Frequently asked questions
Can Cowork connect two Slack workspaces?
No documented path exists. A user-filed request on Anthropic’s public issue tracker, open since April 2026, reports one workspace per Claude account, and a related report describes authorizing one workspace as overwriting the other’s token. Connecting each workspace to Carly is what makes several reachable from one task.
Does Claude Cowork support Slack at all?
Yes, natively, through Slack’s own hosted MCP server. Cowork uses the same connector library as Claude chat, and the connector reads and writes, including searching channels and sending messages.
Is a Slack Connect client the same as a second workspace?
No, and this is the check worth doing first. Slack Connect channels created in your workspace are hosted and owned by your organization, so they are reachable on the single connection Cowork already has.
Does Cowork run when a Slack message arrives?
No. Scheduled tasks run at a cadence you set, and Anthropic’s own example is pull-shaped, summarizing Slack messages, email, or calendar events from the past 24 hours.
Related: What is Claude Cowork · Multiple Slack workspaces in Claude · Claude Cowork plugins · Best AI assistants for Slack
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