Slack Notifier MCP

MCP server for bidirectional Slack communication with Claude Code. Get notified when tasks complete, and respond to Claude's questions directly from Slack.

Quick Start

# Add to Claude Code (one command)
claude mcp add slack-notifier -s user \
  -e SLACK_BOT_TOKEN=xoxb-your-token \
  -e SLACK_DEFAULT_CHANNEL=YOUR-CHANNEL-ID \
  -- uvx slack-notifier-mcp@latest

Features

• Notify - Send notifications when tasks complete, errors occur, or when stepping away
• Ask & Wait - Ask questions and wait for replies via Slack threads
• Bidirectional - Reply to Claude from Slack, get responses back in your terminal
• Urgency Levels - Normal, important, and critical notifications with appropriate formatting

Slack App Setup

Before using this server, you need to create a Slack app:

1. Go to api.slack.com/apps and click Create New App
2. Choose From scratch, name it (e.g., "Claude Code"), and select your workspace
3. Go to OAuth & Permissions in the sidebar
4. Under Scopes > Bot Token Scopes, add:
   • chat:write - Send messages
   • channels:history - Read public channel messages
   • groups:history - Read private channel messages
   • im:history - Read DM messages
   • users:read - Get user display names
5. Click Install to Workspace at the top
6. Copy the Bot User OAuth Token (starts with xoxb-)

To get your default channel ID:

• Open Slack, right-click the channel, and select View channel details
• At the bottom, copy the Channel ID (starts with C)

Installation

Claude Code (Recommended)

claude mcp add slack-notifier -s user \
  -e SLACK_BOT_TOKEN=xoxb-your-token \
  -e SLACK_DEFAULT_CHANNEL=YOUR-CHANNEL-ID \
  -- uvx slack-notifier-mcp@latest

VS Code

code --add-mcp '{"name":"slack-notifier","command":"uvx","args":["slack-notifier-mcp@latest"],"env":{"SLACK_BOT_TOKEN":"xoxb-your-token","SLACK_DEFAULT_CHANNEL":"YOUR-CHANNEL-ID"}}'

Other MCP Clients

{
  "mcpServers": {
    "slack-notifier": {
      "command": "uvx",
      "args": ["slack-notifier-mcp@latest"],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token",
        "SLACK_DEFAULT_CHANNEL": "YOUR-CHANNEL-ID"
      }
    }
  }
}

{
  "mcpServers": {
    "slack-notifier": {
      "command": "uvx",
      "args": ["slack-notifier-mcp@latest"],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token",
        "SLACK_DEFAULT_CHANNEL": "YOUR-CHANNEL-ID"
      }
    }
  }
}

{
  "mcpServers": {
    "slack-notifier": {
      "command": "uvx",
      "args": ["slack-notifier-mcp@latest"],
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token",
        "SLACK_DEFAULT_CHANNEL": "YOUR-CHANNEL-ID"
      }
    }
  }
}

Local Development

git clone https://github.com/strand-ai/slack-notifier-mcp.git
cd slack-notifier-mcp
uv sync
uv run slack-notifier-mcp

MCP Tools

notify

Send a notification to Slack.

notify(
    message="GPU instance is ready! SSH: ubuntu@192.168.1.100",
    urgency="important"  # or "normal", "critical"
)

Parameters:

• message (required): Notification text (supports Slack mrkdwn)
• channel (optional): Channel ID or name (uses default if not set)
• urgency (optional): normal, important, or critical

ask_user

Send a question and wait for the user's reply.

ask_user(
    question="Should I use PostgreSQL or SQLite for the database?",
    context="Setting up the backend for the new API",
    timeout_minutes=10
)
# Returns: {"success": True, "reply": "Use PostgreSQL", ...}

Parameters:

• question (required): The question to ask
• channel (optional): Channel ID or name
• context (optional): Additional context about what you're working on
• timeout_minutes (optional): How long to wait (default 5, max 30)

send_message

Lower-level message sending for conversational use.

send_message(
    message="Done with the first step, moving on...",
    thread_ts="1234567890.123456"  # Reply in thread
)

get_thread_replies

Check for new replies in a thread.

get_thread_replies(
    channel="YOUR-CHANNEL-ID",
    thread_ts="1234567890.123456",
    since_ts="1234567891.000000"  # Only newer messages
)

Environment Variables

Example Usage

Tell Claude Code:

"Notify me on Slack when the tests finish running"

"Ask me on Slack whether to proceed with the database migration"

"Send a Slack notification if any errors occur while I'm away"

Debugging

Run the MCP inspector to test tools:

npx @anthropics/mcp-inspector uvx slack-notifier-mcp@latest

Check if your token works:

curl -H "Authorization: Bearer xoxb-your-token" \
  https://slack.com/api/auth.test

Development

# Install with dev dependencies
uv sync --extra dev

# Run tests
uv run pytest

# Format code
uv run black slack_mcp
uv run ruff check slack_mcp --fix

License

MIT