Slack Notify

MCP server for sending notifications to Slack using OAuth bot tokens.

Features

• Send formatted messages to Slack channels with title and description
• Mention specific users automatically with the mention parameter
• Support for Slack's markdown formatting
• Clean message formatting with optional header
• TypeScript support with full type safety

Installation

npm install @mkusaka/mcp-server-slack-notify
# or
pnpm add @mkusaka/mcp-server-slack-notify

Configuration

Creating a Slack App

1. Create a new Slack app

   • Go to https://api.slack.com/apps
   • Click "Create New App"
   • Choose "From scratch"
   • Enter your app name (e.g., "MCP Notification Bot")
   • Select your workspace
   • Click "Create App"

2. Configure OAuth scopes

   • In your app settings, navigate to "OAuth & Permissions" in the sidebar
   • Scroll down to "Scopes" section
   • Under "Bot Token Scopes", click "Add an OAuth Scope"
   • Add the following scope:
     • chat:write - Required for sending messages

3. Install the app to your workspace

   • Stay on the "OAuth & Permissions" page
   • Click "Install to Workspace" at the top
   • Review the permissions and click "Allow"
   • You'll be redirected back to the OAuth & Permissions page

4. Get your Bot Token

   • After installation, you'll see a "Bot User OAuth Token" on the OAuth & Permissions page
   • It starts with xoxb-
   • Copy this token - you'll need it for the SLACK_BOT_TOKEN environment variable

5. Invite the bot to channels

   • In Slack, go to the channel where you want to send notifications
   • Type /invite @YourBotName (replace with your bot's name)
   • Or click the channel name → "Integrations" tab → "Add apps" → Select your bot

Environment Variables

Set the following environment variables:

• SLACK_BOT_TOKEN (required): Your Bot User OAuth Token from step 4
• SLACK_DEFAULT_CHANNEL (optional): Default channel for notifications (e.g., #general)
• SLACK_MENTIONS (optional): Default user IDs to mention in all messages (e.g., U1234567890,U0987654321)

Usage with Claude Desktop

Add to your Claude Desktop configuration:

{
  "mcpServers": {
    "slack-notify": {
      "command": "npx",
      "args": ["-y", "@mkusaka/mcp-server-slack-notify@latest"],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token-here",
        "SLACK_DEFAULT_CHANNEL": "#general",
        "SLACK_MENTIONS": "U1234567890,U0987654321"
      }
    }
  }
}

Usage with Claude Code

You can add this MCP server to Claude Code using the following command:

claude mcp add slack-notify -e SLACK_BOT_TOKEN=xoxb-your-token-here -e SLACK_DEFAULT_CHANNEL=#general -e SLACK_MENTIONS=U1234567890,U0987654321 -- npx -y @mkusaka/mcp-server-slack-notify@latest

Or if you have the package installed globally:

# Install globally first
npm install -g @mkusaka/mcp-server-slack-notify

# Then add to Claude Code
claude mcp add slack-notify -e SLACK_BOT_TOKEN=xoxb-your-token-here -e SLACK_DEFAULT_CHANNEL=#general -e SLACK_MENTIONS=U1234567890,U0987654321 -- mcp-server-slack-notify

To add with user scope (available across all projects):

claude mcp add --scope user slack-notify -e SLACK_BOT_TOKEN=xoxb-your-token-here -e SLACK_DEFAULT_CHANNEL=#general -e SLACK_MENTIONS=U1234567890,U0987654321 -- npx -y @mkusaka/mcp-server-slack-notify@latest

Available Tools

send_slack_notification

Sends a notification to a Slack channel.

Parameters:

• channel (optional): The Slack channel (e.g., #general or C1234567890)
• title (optional): The notification title (if provided, displays with header formatting)
• description (required): The notification body (supports Slack markdown)
• mention (optional): User ID(s) to mention. Can be a single user ID (e.g., U1234567890) or multiple IDs separated by commas (e.g., U1234567890,U0987654321)

Formatting Guide

The description field supports Slack's mrkdwn formatting:

• Mentions:
  • User: <@U1234567890> (use the user's ID)
  • Channel: <#C1234567890> (use the channel's ID)
  • @here: <!here>
  • @channel: <!channel>
  • User groups: <!subteam^S1234567890> (use the subteam's ID)
  • Note: When using the mention parameter or SLACK_MENTIONS environment variable, user mentions are automatically added at the beginning of the message
• Text formatting:
  • Bold: *bold text*
  • Italic: _italic text_
  • Strikethrough: ~strikethrough text~
  • Code: `inline code`
  • Code block: ```code block```
  • Quote: > quoted text
  • Link: <https://example.com|Link text>

Development

# Install dependencies
pnpm install

# Run tests
pnpm test

# Build
pnpm build

# Run in development mode
pnpm start

# Debug with MCP Inspector
pnpm debug

Testing

The project includes comprehensive tests using Vitest with mocked Slack API calls.

# Run tests
pnpm test

# Run tests in watch mode
pnpm test:watch

License

MIT