Slack MCP Server (Advanced)

MCP Server for the Slack API, enabling Claude to interact with Slack workspaces, including private channels.

Tools

1. slack_list_channels

   • List public, private (if bot is invited), or pre-defined channels in the workspace.
   • Optional inputs:
     • limit (number, default: 100, max: 200): Maximum number of channels to return
     • cursor (string): Pagination cursor for next page
   • Returns: List of channels with their IDs and information

2. slack_post_message

   • Post a new message to a Slack channel
   • Required inputs:
     • channel_id (string): The ID of the channel to post to
     • text (string): The message text to post
   • Optional inputs (requires chat:write.customize scope):
     • username (string): Custom display name for this message
     • icon_url (string): URL to an image to use as the avatar
     • icon_emoji (string): Emoji code (like :robot_face:) to use as the avatar
   • Returns: Message posting confirmation and timestamp

3. slack_reply_to_thread

   • Reply to a specific message thread
   • Required inputs:
     • channel_id (string): The channel containing the thread
     • thread_ts (string): Timestamp of the parent message
     • text (string): The reply text
   • Optional inputs (requires chat:write.customize scope):
     • username (string): Custom display name for this message
     • icon_url (string): URL to an image to use as the avatar
     • icon_emoji (string): Emoji code (like :robot_face:) to use as the avatar
   • Returns: Reply confirmation and timestamp

4. slack_add_reaction

   • Add an emoji reaction to a message
   • Required inputs:
     • channel_id (string): The channel containing the message
     • timestamp (string): Message timestamp to react to
     • reaction (string): Emoji name without colons
   • Returns: Reaction confirmation

5. slack_get_channel_history

   • Get recent messages from a channel
   • Required inputs:
     • channel_id (string): The channel ID
   • Optional inputs:
     • limit (number, default: 10): Number of messages to retrieve
   • Returns: List of messages with their content and metadata

6. slack_get_thread_replies

   • Get all replies in a message thread
   • Required inputs:
     • channel_id (string): The channel containing the thread
     • thread_ts (string): Timestamp of the parent message
   • Returns: List of replies with their content and metadata

7. slack_get_users

   • Get list of workspace users with basic profile information
   • Optional inputs:
     • cursor (string): Pagination cursor for next page
     • limit (number, default: 100, max: 200): Maximum users to return
   • Returns: List of users with their basic profiles

8. slack_get_user_profile

   • Get detailed profile information for a specific user
   • Required inputs:
     • user_id (string): The user's ID
   • Returns: Detailed user profile information

9. slack_edit_message

   • Edit an existing message posted by the bot
   • Required inputs:
     • channel_id (string): The ID of the channel containing the message
     • ts (string): Timestamp of the message to edit
     • text (string): The new text for the message
   • Optional inputs (requires chat:write.customize scope):
     • username (string): Custom display name for this message
     • icon_url (string): URL to an image to use as the avatar
     • icon_emoji (string): Emoji code (like :robot_face:) to use as the avatar
   • Returns: Message update confirmation

Setup

1. Create a Slack App:

   • Visit the Slack Apps page
   • Click "Create New App"
   • Choose "From scratch"
   • Name your app and select your workspace

2. Configure Bot Token Scopes: Navigate to "OAuth & Permissions" and add these scopes:

   • channels:history - View messages and other content in public channels
   • channels:read - View basic public channel information
   • groups:read - View basic private channel information (needed for slack_list_channels)
   • chat:write - Send messages as the app
   • chat:write.customize - Send messages with a custom username and avatar
   • reactions:write - Add emoji reactions to messages
   • users:read - View users and their basic information
   • users.profile:read - View user profile details (needed for slack_get_user_profile)

3. Install App to Workspace:

   • Click "Install to Workspace" and authorize the app
   • Save the "Bot User OAuth Token" that starts with xoxb-

4. Get your Team ID (starts with a T) by following this guidance

Usage with Claude Desktop

Add the following to your claude_desktop_config.json:

npx

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": [
        "-y",
        "@nlile/server-slack-advanced"
      ],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-bot-token",
        "SLACK_TEAM_ID": "T01234567",
        "SLACK_CHANNEL_IDS": "C01234567,G76543210"
      }
    }
  }
}

docker

{
  "mcpServers": {
    "slack": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "SLACK_BOT_TOKEN",
        "-e",
        "SLACK_TEAM_ID",
        "-e",
        "SLACK_CHANNEL_IDS",
        "nlile/server-slack-advanced" // update image name if you build it
      ],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-bot-token",
        "SLACK_TEAM_ID": "T01234567",
        "SLACK_CHANNEL_IDS": "C01234567,G76543210" // can be public (C...) or private (G...)
      }
    }
  }
}

Environment Variables

1. SLACK_BOT_TOKEN: Required. The Bot User OAuth Token starting with xoxb-.
2. SLACK_TEAM_ID: Required for listing all channels or users. Your Slack workspace ID starting with T.
3. SLACK_CHANNEL_IDS: Optional. Comma-separated list of specific channel IDs (public C... or private G...) to limit access to. If set, only these channels will be visible/accessible via the tools. If not set, slack_list_channels will list all public channels and private channels the bot has been invited to (requires groups:read scope). The bot must be explicitly invited to any private channels it needs to interact with, regardless of this setting.

Troubleshooting

If you encounter permission errors, verify that:

1. All required scopes (including groups:read for private channels) are added to your Slack app.
2. The app is properly installed/reinstalled to your workspace after scope changes.
3. The tokens and workspace ID are correctly copied to your configuration.
4. The app has been added (/invite @YourBotName) to the specific private channels it needs to access.

Build

Docker build:

# update tag as needed
docker build -t nlile/server-slack-advanced:latest -f src/slack/Dockerfile .

Testing Locally

1. Build the code: npm run build --workspace src/slack
2. Pack the package: cd src/slack && npm pack
   • This creates a .tgz file (e.g., nlile-server-slack-advanced-0.0.3.tgz).
3. Install globally (for testing): e.g. npm install -g nlile-server-slack-advanced-0.0.{x}.tgz
4. Run the server:

   export SLACK_BOT_TOKEN="your-token"
   export SLACK_TEAM_ID="your-team-id"
   mcp-server-slack-advanced

5. Test with an MCP client (like Claude Desktop or a script) to ensure it connects and tools work.
6. Uninstall: npm uninstall -g @nlile/server-slack-advanced

Publishing to NPM

1. Ensure clean git status: git status (commit or stash changes).
2. Login to npm: npm login (if not already logged in).
3. Bump version: cd src/slack && npm version patch (or minor/major). This updates package.json and creates a git commit/tag.
4. Push git changes: git push && git push --tags
5. Publish: cd src/slack && npm publish --access public (use --access public for scoped packages on the free tier).

License

This MCP server is licensed under the MIT License.