How to Connect Multiple Slack Workspaces to Claude

You connect Slack to Claude, and it works until you try to add a client's workspace and find that Claude has no option for it.

Claude's built-in Slack connector supports one workspace per Claude account, so you cannot add a second workspace through the user interface or configuration.

If you work as a consultant, contractor, advisor, or agency, you probably know this limitation and understand how much time you could save if Claude could work with several Slack workspaces.

This guide shows you how to use Composio to connect multiple Slack workspaces to Claude.

Related: How to connect multiple Gmail accounts to Claude

The limit, precisely

An open feature request on Anthropic's tracker explains the limit clearly: the built-in Slack MCP connector supports only one workspace per Claude account, so you cannot add a second workspace through the user interface or configuration. The request describes a consultant who uses a company workspace and a client workspace, and it also describes a founder who advises other companies.

The issue also explains how much work is required to connect a second workspace. You can connect the first workspace with one click, but to connect the second one, you must set up a self-hosted MCP server, download a third-party binary, create a Slack app at api.slack.com, configure seven OAuth scopes, add the correct CLI flags to the MCP JSON configuration, and restart your client. You must complete all these steps for one additional workspace.

You also cannot add the same connector twice with a different name for each workspace because Claude rejects a server URL that is already registered.

The request remains open, and Anthropic has not announced when it will provide this feature.

What you'll build

With this setup, you add one custom connector to Claude, and it gives you access to every Slack workspace that you use. You label each connection with the client's name, so you can use prompts such as:

In comp-slack (CLIENT), find the last three messages in #design-review that mention the navigation redesign. Do not post anything, and include the channel and timestamp for each message.
I have a call with Northwind in 20 minutes, so use only northwind-slack and tell me what has changed since Thursday and what they need from us.

Composio makes this setup possible because it stores several Slack connections, gives each one a label, and makes them available to Claude through one connector.

Before you start

Claude:

• You can use custom connectors on the Free, Pro, Max, Team, and Enterprise plans, but the Free plan allows only one custom connector, so Composio must use that slot.

• If you use a Team or Enterprise plan, an Owner must add the connector for the organisation, and each member must then connect their own account.

Composio:

• You need a free Composio account, which includes 100K tool calls each month and unlimited connections without a payment card.

• Use an account that your agency owns, so the client connections remain available if the person who sets them up leaves.

Client access:

• You need permission to install apps in each client workspace, or you need an administrator who can approve the request. Many client workspaces restrict app installation, so ask for approval before you start.

Time: Allow approximately 6 minutes to add the connector and 1–2 minutes for each workspace, plus the time that each approval takes.

Step 1 — Add Composio as a custom connector

Composio provides one shared MCP endpoint, and everyone uses the same URL while Composio manages authentication through OAuth.

1. In Claude, open Customize → Connectors at https://claude.ai/customize/connectors.

2. Click the + button, and then select Add custom connector.

1. Enter these values:

   • Name: Composio

   • URL: https://connect.composio.dev/mcp

   • Advanced settings: Leave these fields empty because Composio manages the client ID, secret, headers, and authentication.

2. Click Add and then Connect. When a browser window opens, sign in to Composio or create a free account, and then approve the request.

3. Return to Claude and make sure that Composio has a CUSTOM badge and is switched on.

Check the connection. Start a new chat and ask, "What Composio tools do you have available?" Claude should show a short list of meta-tools that find and run the correct tool when you need it. This design lets one connector provide access to more than 1,000 apps while it keeps the context small.

Step 2 — Pick your Slack toolkit (do this before connecting)

Composio provides two Slack toolkits, so choose the one that gives you the access you need.

For agency reports that ask what a client said about a topic, slackbot is usually more useful because standard bot scopes can read only the channels where someone invited the app.

Review access to direct messages carefully. Access to direct messages in a client's workspace can create additional privacy and security requirements, so use the narrower slack toolkit or get the client's written approval before you use slackbot.

Step 3 — Connect your first workspace

You can connect each workspace from a Claude chat, so start a new conversation and enter this prompt:

Connect my agency's Slack workspace to Composio, and label it internal-slack.

Claude gives you an authorisation link. Open it, select the correct workspace on the Slack OAuth screen, review the permissions, and approve the request.

Return to Claude, and it will check the connection until the status changes to Active.

Composio calls the label an alias, and Claude uses it to send each future request to the correct workspace. Each alias must be unique within its toolkit.

Step 4 — Connect the second, third, fourth workspace

Continue in the same conversation and enter this prompt:

Connect another Slack workspace, and label it comp-slack.

Composio creates a new connection and gives you a new authorisation link, while your first connection remains available. After you approve the new connection, ask Claude to list your Slack connections and confirm that both appear.

Select the correct workspace

Slack shows a workspace dropdown in the top-right corner of the authorisation screen, and it can select one of your signed-in workspaces automatically. Check this dropdown every time because you can easily approve the wrong workspace.

Use one of these methods to make the process reliable:

• Open the dropdown and select the intended workspace before you approve the request.

• Use a separate browser profile for each client, and open the authorisation link in the matching profile.

• Open the link in an incognito window, and then sign in to the intended workspace.

Repeat this process for each client. Composio limits the number of accounts for each toolkit, and the SDK default is 5 accounts, although you can configure a value from 2 to 10. If your agency has more than five active Slack clients, increase the limit or use separate Composio projects.

Step 5 — Verify before you trust it

Verify the connections before you use them for client work, and start with this prompt:

List all my connected Slack accounts in Composio, and include the alias and status for each account.

A connection can run tools only when its status is ACTIVE. Then use this prompt to check where every alias points:

For each connected Slack account, show its alias and the name of the workspace that authorised it.

Check the results carefully because two aliases can point to the same workspace, and this error can make Claude return information from the wrong client.

Step 6 — The Composio dashboard flow

Chat is the quickest way to connect a workspace, while the dashboard helps you audit, rename, revoke, and troubleshoot connections. Open dashboard.composio.dev, and sign in with the account that you authorised in Step 1.

Choose the correct dashboard area

The Composio dashboard has two areas, and each area contains different resources:

Resources from one area do not appear in the other area, so use the product switcher if you cannot find your Slack connections.

Connect workspaces in For You

Use this method when you want to connect several clients in one session:

1. Open For You from the product switcher.

2. Find Slack in the app list.

1. Click Connect, and complete the Slack OAuth process.

1. Click Connect on Slack again (Connect New) to add the next workspace, and then give the connection a clear client label.

2. Check the workspace dropdown before you approve each connection, as described in Step 4.

You can also rename, disconnect, or delete a connection from this screen, and you can re-authorise an expired connection. Composio refreshes tokens automatically, but you must reconnect a workspace if its refresh token is revoked or expires and its status changes to EXPIRED.

Review activity in Platform

In Platform, the Logs area shows the request, response, error, version, and Log ID for each tool call. Composio keeps these logs for 7 days on Free and 30 days on Pro. The Auth Configs area stores the OAuth configuration for each toolkit, including custom scopes when you use your own Slack app.

Learn where these logs are before a client asks whether your AI accessed their Slack on a specific date.

Step 7 — Naming, and how not to leak client data

The access rules are as important as the setup because Claude can reach several client workspaces, and an unclear request can send it to the wrong one.

Use one alias format

Choose a clear format and use it for every connection:

<client>-slack

Examples include comp-slack, northwind-slack, and internal-slack. Clear aliases help Claude select the correct workspace, while names such as slack2 or client-slack can cause confusion.

Give Claude the workspace map and rules

Add this block to your Claude personal preferences, or add a separate version to each client project:

Connected Slack workspaces:
internal-slack = our agency
comp-slack = Comp Corp (client)
northwind-slack = Northwind (client)

Rules:

1. Use client workspaces for reading, and show me a draft if I ask for a post, reply, reaction, or message.
2. State the source workspace and channel for every fact that you report.
3. You can move client information to our internal workspace, but you must never move it to another client's workspace.
4. Ask me which workspace to use if I do not name one and the request could apply to several workspaces.

Rule 3 prevents information from moving between clients, and Rule 4 prevents Claude from using the most recently connected account when your request does not specify a workspace.

Use one Claude project for each client

Aliases control routing, and projects make it easier to repeat the correct routing. When you create one project for each client and add that client's rules to its instructions, every new chat starts with the correct context, and each account-team member receives the same guardrails.

Disable Claude's built-in Slack connector

If Claude can use both Anthropic's Slack connector and Composio, it has two routes to Slack and can select the route that sees only one workspace. Open Customise → Connectors, disconnect the built-in Slack connector, and use Composio as the single route.

Prompts that earn the setup

Review unresolved client questions:

In comp-slack and northwind-slack, find unresolved questions that clients sent to our team during the last 7 days. Group the results by client, include the channel and timestamp, and use read-only actions.

Find an earlier decision:

Search comp-slack for the thread where we agreed on the launch date, and show me the message, author, and timestamp without sending a reply.

Check for urgent messages:

Search all connected client workspaces for messages from the last 48 hours that might need a response today, and include the workspace name with every item.

Prepare a draft:

Find the latest message in #design-review in comp-slack, and draft a reply here without posting it.

When you ask Claude to post an approved message, it first checks whether the channel exists, then sends the message with the mention. Open the Slack channel to confirm that the message arrived.

Troubleshooting

Composio tools do not appear in Claude.

1. Open Customise → Connectors, and make sure that Composio has a CUSTOM badge and is switched on.

2. Click ⋮ next to Composio, and select Clear cache.

3. If the tools still do not appear, select ⋮ → Disconnect, remove the connector, and then add it again.

The authorisation link expired or did not open.
Composio OAuth links expire quickly, so ask Claude to retry the connection and generate a new link rather than using an earlier one from the conversation.

Two aliases point to the same workspace.
Delete the duplicate connection in the dashboard, then reconnect it in an incognito window while carefully selecting the correct workspace.

Search cannot find messages in a channel that you can read.
Standard bot scopes can read only the channels where someone added the app, so invite it to the channel or use slackbot for workspace-wide read access.

Slack AI search fails.
The assistant.search.context scope works only when the OAuth app has the Agents & AI Apps feature enabled and the workspace uses the Business+ plan or a higher plan. Configuration changes cannot enable this feature on a lower Slack plan.

Channel administration actions fail.
The admin.conversations:write scope requires an Enterprise Slack plan, so check the client's plan before you use actions such as deleting conversations.

A Slack action returns an authentication error.
Ask Claude to inspect the connection, and reconnect that workspace if its status is unhealthy or expired. Then retry the action, and review Logs in Platform if you need the complete error response.

Claude used the wrong client workspace.
Use the workspace alias in every request, and add the workspace map and rules to the project instructions so the error does not happen again.

Add custom connector is unavailable.
The Free plan allows one custom connector, so the option can be unavailable if you already use that slot. On Team and Enterprise plans, an Owner must add the connector.

Offboarding a client

1. Delete the Composio connection. Open Dashboard → For You, find comp-slack, and disconnect it. Composio deletes the connection immediately.

1. Revoke access in the client's workspace. Ask the workspace administrator to remove the app from Slack app management, as deleting your Composio connection might leave the Slack grant active.

2. Remove the client's workspace map. Delete the client's block from your Claude project instructions so Claude cannot refer to an old alias.

3. Confirm the change in writing. Send a short message such as, "We revoked our AI assistant's access to your Slack on [date]."

This process lets you remove one client's access in approximately two minutes and provides a clear record for the client's next security review.

Costs and honest limits

Composio Free: The Free plan includes 100K tool calls each month, unlimited connections, 50K trigger events, and 3 team members. It has a fixed limit and does not require a payment card, so an agency with five clients and daily reviews is unlikely to exceed it. If you need more usage, Pro costs $29 each month and includes usage credit.

Limits of this setup:

• Claude starts work when you open a conversation. Connectors do not monitor Slack continuously or send an automatic alert when a client posts in #urgent, so you need another type of automation for that workflow.

• Each toolkit has an account limit. The default is 5 accounts, and you can configure a value from 2 to 10. Use separate Composio projects if you need more accounts.

• Slack plan limits still apply. Business+ and Enterprise features remain unavailable when a client uses a lower Slack plan.

• Claude keeps the permissions of the connected identity. It cannot access data or perform actions that the connected identity cannot access.

• Composio becomes an additional vendor. It is SOC 2 Type 2 and ISO 27001 compliant, and it uses OAuth tokens that are encrypted during transfer and storage, so it does not store client passwords. Tell clients about this vendor before their security review.

FAQ

Can Claude connect to two Slack workspaces natively?

No. One workspace per Claude account, with no UI or configuration path to a second, per Anthropic's own open issue.

Can I add the built-in connector twice under different names?

No. Claude rejects a server URL that's already registered.

Does this work in Cowork and Claude Code?

Yes. Cowork uses the same Customise → Connectors flow. Claude Code takes the same endpoint as an HTTP MCP server, or Composio's native agent plugin via the CLI, which is the shorter path for coding agents.

Do my workspaces get merged?

No. Each connection keeps its own token and stays separately addressable. That's exactly why routing by alias works.

How many workspaces can I connect?

The default cap is 5 per toolkit, configurable from 2 to 10.

Can each person on my team have their own connections?

Yes. Composio scopes connections per user, so two people never touch each other's credentials. Shared connections also support per-user access control if you'd rather have one agency-held connection per client.

Will clients see we've connected something?

Yes, and they should. Installed apps are visible to Slack workspace admins. Tell them first.

What about Notion, Linear, Google Drive?

Same connector, same pattern, same multi-account behaviour. Most agency setups end up with three or four apps per client, all behind a single connector.