Slack MCP Server

A MCP (Model Context Protocol) server for interacting with Slack.

Security Features

• Link Unfurling Disabled: Prevents automatic link crawling that could leak sensitive information
• Rate Limiting: Enforces 60 requests per minute per endpoint
• Markdown Conversion: Automatically converts GitHub Flavored Markdown to Slack mrkdwn format

Slack Setup

1. Create a Slack App:

   • Visit the Slack Apps
   • 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 channel information
   • chat:write - Send messages as the app
   • reactions:write - Add emoji reactions to messages
   • users:read - View users and their basic information
   • users.profile:read - View detailed profiles about users

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)

MCP Server Configuration

Add to mcp.json servers configuration:

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": [
        "-y",
        "@axivo/mcp-slack"
      ],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-bot-token",
        "SLACK_TEAM_ID": "T01234567",
        "SLACK_CHANNEL_IDS": "C01234567, C76543210"
      }
    }
  }
}

Environment Variables

Required variables:

• SLACK_BOT_TOKEN - Slack bot token (starts with xoxb-)
• SLACK_TEAM_ID - Slack Team ID (starts with T)

Optional variables:

• SLACK_CHANNEL_IDS - Comma-separated list of channel IDs to restrict access to specific channels only. If not set, the server can access all public channels the bot has permissions for.

Prompt Examples

Here are practical examples of how to use the Slack MCP server with natural language prompts:

• "Mention my name into #general Slack channel and post a project update"
• "Read the last 20 messages from #marketing Slack channel to catch up on discussions"
• "Reply to the latest thread in #support Slack channel with a solution"
• "Add a thumbs up reaction to the latest message in #announcements Slack channel"
• "Get all replies from that long thread about the API changes"
• "Edit my last message in #general Slack channel to fix the typo"
• "List all channels I have access to and find the engineering-related ones"
• "Look up John's profile information and timezone"

MCP Tools

1. add_reaction

   • Add a reaction emoji to a message
   • Required inputs:
     • channel_id (string): The ID of the channel containing the message
     • timestamp (string): The timestamp of the message to react to
     • reaction (string): The name of the emoji reaction (without ::)
   • Returns: Reaction addition confirmation

2. edit_message

   • Edit an existing message in a Slack channel
   • Required inputs:
     • channel_id (string): The ID of the channel containing the message
     • timestamp (string): The timestamp of the message to edit
     • text (string): The message text to edit
   • Returns: Message edit confirmation with updated content

3. get_channel_history

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

4. get_thread_replies

   • Get all replies in a message thread
   • Required inputs:
     • channel_id (string): The ID of the channel containing the thread
     • thread_ts (string): The timestamp of the parent message in the format '1234567890.123456'. Timestamps in the format without the period can be converted by adding the period such that 6 numbers come after it
   • Returns: Array of thread replies with message details

5. get_user_profile

   • Get detailed profile information for a specific user
   • Required inputs:
     • user_id (string): The ID of the user
   • Returns: Detailed user profile information including display name, status, timezone, etc.

6. get_users

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

7. list_channels

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

8. 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
   • Returns: Message posting confirmation with timestamp and channel info

9. reply_to_thread

   • Reply to a specific message thread in Slack
   • Required inputs:
     • channel_id (string): The ID of the channel containing the thread
     • thread_ts (string): The timestamp of the parent message in the format '1234567890.123456'. Timestamps in the format without the period can be converted by adding the period such that 6 numbers come after it
     • text (string): The reply text to post
   • Optional inputs:
     • broadcast (boolean, default: false): Whether to also send the reply to the main channel
   • Returns: Thread reply confirmation with message details