Slack MCP Server

A Model Context Protocol (MCP) server for integrating with Slack workspaces. This server provides tools for reading and writing messages, managing threads, and reacting to messages in Slack.

Features

• List Channels - View all accessible public and private channels
• Read Channel - Get channel info and recent messages
• Read Threads - Get full threaded conversations
• Post Messages - Send new messages to channels
• Reply to Threads - Continue threaded conversations
• Update Messages - Edit previously posted messages
• React to Messages - Add emoji reactions to messages

Installation

npm install slack-workspace-mcp-server

Or run directly with npx:

npx slack-workspace-mcp-server

Configuration

Required Environment Variables

| Variable | Description | Example | | ----------------- | -------------------------- | -------------- | | SLACK_BOT_TOKEN | Slack Bot User OAuth Token | xoxb-1234... |

Optional Environment Variables

| Variable | Description | Default | | -------------------- | ----------------------------------- | ----------- | | ENABLED_TOOLGROUPS | Comma-separated list of tool groups | All enabled |

Getting a Bot Token

1. Go to api.slack.com/apps
2. Create a new app or select an existing one
3. Navigate to OAuth & Permissions
4. Add the following Bot Token Scopes:
   • channels:read - View basic channel information
   • channels:history - View messages in public channels
   • groups:read - View private channels
   • groups:history - View messages in private channels
   • chat:write - Send messages
   • reactions:write - Add reactions
5. Install the app to your workspace
6. Copy the Bot User OAuth Token (starts with xoxb-)

MCP Client Configuration

For Claude Desktop, add to your configuration:

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": ["slack-workspace-mcp-server"],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token-here"
      }
    }
  }
}

Available Tools

Read-Only Tools

| Tool | Description | | -------------------- | ------------------------------------- | | slack_get_channels | List all accessible channels | | slack_get_channel | Get channel info with recent messages | | slack_get_thread | Get a thread with all replies |

Write Tools

| Tool | Description | | ------------------------ | ---------------------------------- | | slack_post_message | Post a new message to a channel | | slack_reply_to_thread | Reply to an existing thread | | slack_update_message | Update a previously posted message | | slack_react_to_message | Add an emoji reaction to a message |

Tool Groups

You can control which tools are available using the ENABLED_TOOLGROUPS environment variable:

• readonly - Only read operations (get channels, messages, threads)
• write - All operations including posting and reactions

Example: ENABLED_TOOLGROUPS=readonly to disable all write operations.

Development

# Install dependencies
npm run install-all

# Run in development mode
npm run dev

# Run tests
npm test                  # Functional tests
npm run test:integration  # Integration tests
npm run test:manual       # Manual tests (requires real credentials)

# Build
npm run build

License

MIT