How to Connect Multiple Slack Workspaces to Claude
Claude’s built-in Slack connector holds one workspace per Claude account. Anyone consulting, advising, or contracting hits this immediately, because the second workspace is where half the work lives. Connecting each workspace to Carly and adding Carly to Claude keeps all of them reachable from one conversation.
The limit, stated by Anthropic’s own tracker
The open feature request Support multiple Slack workspaces in the built-in Slack connector puts it plainly: “The built-in Slack MCP connector currently supports only one workspace per Claude account. There is no way to add a second workspace through the UI or configuration.”
The same issue describes what reaching a second workspace costs today. Connecting the first is one click. Connecting the second means “setting up a self-hosted MCP server from scratch: downloading a third-party binary, creating a Slack app manually at api.slack.com, configuring seven OAuth scopes, writing MCP JSON config with the correct CLI flags, and restarting Claude Code.”
This is not unique to Anthropic. OpenAI’s open request for multiple named accounts per app/connector observes that “Slack is documented as one workspace at a time, requiring disconnect/reconnect to switch workspaces,” and that the connector model generally “appears oriented around one active connection per provider.”
What connecting every workspace changes
One Claude conversation can:
- search several workspaces at once and cite which one each result came from;
- pull the week’s decisions out of client and internal channels together;
- summarize a thread in one workspace and post the summary in another;
- draft or send a message in the exact workspace and channel you name;
- watch for a keyword across workspaces rather than one at a time;
- match a Slack thread to the related email or calendar event.
The workspaces stay separate, each with its own authorization and permissions.
1. Give each workspace a role
| Workspace | Role |
|---|---|
example-internal | Internal |
example-client-northwind | Client |
example-founders | Community |
Roles are easier to use mid-sentence than workspace URLs, and they make it obvious when an instruction is about to cross a boundary you care about.
2. Connect the first Slack workspace to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Slack and click Connect.
- Choose the first workspace at Slack’s authorization screen.
- Review the requested scopes and approve.
- Confirm the workspace name in Carly.
If the workspace restricts app installation, ask a Slack workspace owner or admin to approve Carly first.
3. Add the other Slack workspaces
- Return to Carly’s integrations page.
- Select Slack → Connect again.
- At Slack’s authorization screen, switch to the next workspace before approving. Slack preselects whichever workspace you used last, so check the name at the top of the consent screen.
- Approve the scopes.
- Confirm the workspace appears in Carly under its own name.
- Repeat for every remaining workspace.
Client workspaces you were invited to as a guest connect the same way, limited to the channels your account can already see.
4. Add Carly to Claude
- Open Settings → Connectors in Claude.
- Choose Add custom connector.
- Paste
https://carlyassistant.com/mcp/. - Continue to authorization.
- Sign in to the Carly account holding the Slack connections.
- Enable the connector for your conversations.
On a Team or Enterprise plan, an administrator may need to allow custom connectors before this appears.
5. Test each workspace read-only
Keep Claude reading before it writes:
In the
example-client-northwindworkspace, list the five most recent messages in #general with sender and timestamp. Do not post anything.
In the
example-internalworkspace, find the newest thread mentioning “launch date.” State the workspace and channel and do not reply.
Then span workspaces:
Search the Northwind and internal example workspaces for “contract” in the last 14 days. Include the workspace and channel on every row.
6. Reuse this routing prompt
Treat
example-internalas Internal,example-client-northwindas Client, andexample-foundersas Community. Never post in a Client workspace without asking first. Always state the workspace and channel before sending anything.
Then name the target on each action:
Post the release note in
example-internal, channel #announcements. Show me the draft first.
Reply in the Northwind example thread only. Do not cross-post to any other workspace.
That last instruction matters more here than in a single-workspace setup, since the cost of a misrouted message is a client seeing something internal.
Claude’s Slack connector versus Carly
| Need | Claude’s Slack connector | Carly connector |
|---|---|---|
| Search one workspace | Yes | Yes |
| Keep several workspaces connected at once | One per Claude account | Yes |
| Search across workspaces in one question | No | Yes |
| Post to a chosen workspace and channel | The connected workspace only | Yes, within that workspace’s permissions |
| Switch workspaces without reauthorizing | No | Yes |
| Combine Slack with mail and calendar accounts | Separate connectors | Yes, in one instruction |
Carly gives Claude one workspace-aware toolset, and the same connections keep working on a schedule after the conversation ends. Carly offers free Zapier-style workflows; AI agents start at $35/month.
Quick fixes
| Problem | Fix |
|---|---|
| The second workspace replaced the first | Reconnect in Carly and confirm both workspace names are listed |
| Slack authorized the wrong workspace | Check the workspace name at the top of Slack’s consent screen and reconnect |
| Workspace blocks app installation | Ask a Slack owner or admin to approve Carly |
| A private channel is missing | Confirm the connected account is a member, then reconnect |
| Claude answers from the wrong workspace | Require the workspace and channel on every row |
Frequently asked questions
Can Claude connect two Slack workspaces natively?
Not through the built-in connector, which Anthropic’s open issue describes as one workspace per Claude account with no UI or configuration path to a second. Connecting each workspace to Carly and adding Carly to Claude keeps them all available.
Do I need to build my own MCP server?
That is the documented workaround, and it means a self-hosted server, a manually created Slack app, and seven OAuth scopes per workspace. Connecting each workspace to Carly avoids that setup.
Does this work for client workspaces I joined as a guest?
Yes, within your existing permissions. Carly can only reach the channels your Slack account can already see.
Can Slack and email accounts be combined in one instruction?
Yes. Once mail, calendar, and Slack workspaces are connected to Carly, a single instruction can cross them, which is how a thread gets matched to the email or meeting it relates to.
Related: Claude + Slack · Slack MCP · Multiple Gmail accounts in Claude · Connect Slack to an AI agent · Carly’s Slack integration
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