How to use Slack from your MCP Client

This guide demonstrates how to connect your Slack workspace to your MCP Client.

As Slack doesn’t provide an official MCP server, and Anthropic’s reference implementation was deprecated due to security vulnerabilities , this guide uses the open-source slack-mcp-server instead.

After following this guide you’ll be able to read and summarize conversations, search message history, and analyze team communications without leaving Claude Desktop or whatever client you prefer. Here’s an example where Claude finds all messages with reactions in a specific channel:

Prerequisites

To follow along, you’ll need

• A user account on a Slack workspace
• An MCP Client like Claude Desktop
• Ideally some familiarity with editing JSON files and using your browser’s developer tools

Getting your Slack xoxc and xoxd auth tokens

Instead of connecting to the Slack API, which would require admin access, we’ll use the browser session tokens to authorize the Slack MCP Server to connect to your Slack workspace. Your MCP client will then have access to anything that you would in Slack. To get these, you’ll need to log into your Slack workspace using a browser like Google Chrome.

To get the xoxc token:

1. Open the Slack workspace in your browser.

2. Open the developer console by pressing Ctrl+Shift+I (Cmd+Option+I on macOS) or F12.

3. Switch to the Console tab.

4. Type “allow pasting” into the console and press Enter.

5. Paste the following snippet into the console and press Enter:

The token will be returned in the console. It starts with xoxc-. Save this somewhere.

To get the xoxd token:

1. Switch to the Application tab (Storage in Firefox and Safari).
2. In the sidebar, under Storage, click Cookies.
3. Find the cookie named d in the table.
4. Copy the cookie’s value to the clipboard.

The token value starts with xoxd-. Save this somewhere.

Cloning and modifying the project

The Slack MCP Server only recently added support  for reactions, and that functionality is not yet included in their latest release, so we need to clone and build the project locally.

Run the following commands

The build will be located in the root of the cloned project at slack-mcp-server/slack-mcp-server.

Installing the MCP server in Claude

Now update your Claude Desktop configuration to include the MCP server.

Open Claude Desktop and go to Settings > Developer > Edit Config.

In the claude_desktop_config.json file that opens, add the Slack MCP Server configuration:

Replace PATH_TO_MCP_SERVER with the absolute path to your cloned slack-mcp-server directory. Replace YOUR_XOXC_TOKEN and YOUR_XOXD_TOKEN with the Slack tokens you saved previously.

Restart Claude Desktop to load the server.

To test that the connection is working, ask Claude to list the current channels in your Slack workspace.

Testing reaction functionality

In Claude Desktop, start a new chat. Click the Search and tools button to see the MCP server listed. Enable all tools if needed.

Add reaction emojis to messages in your Slack workspace, then ask Claude to show you messages with reactions to test the server’s reaction-reading functionality.

Conclusion

Claude Desktop can now access your Slack workspace and read message reactions through the customized MCP server. While the server can be installed directly using a DXT file , building from source lets you customize functionality for your workflows.