slack-notifier-mcp 0.3.0

MCP server for Slack notifications with bidirectional communication

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

• Send Messages - Send messages with optional urgency levels and thread support
• 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

Claude Desktop

Add to your Claude Desktop config:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

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

Cursor

1. Go to Settings → MCP → Add new MCP Server
2. Select command type
3. Enter command: uvx slack-notifier-mcp@latest
4. Add environment variables for SLACK_BOT_TOKEN and SLACK_DEFAULT_CHANNEL

Or add to ~/.cursor/mcp.json:

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

Windsurf / Other MCP Clients

Any MCP-compatible client can use slack-notifier:

{
  "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

send

Send a message to Slack with optional urgency and thread support.

# Simple message
send(message="Build completed successfully")

# With urgency (adds formatting and @here for critical)
send(
    message="Server is down!",
    urgency="critical"  # or "normal", "important"
)

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

# Mention user
send(
    message="Need your attention",
    mention_user=True
)

Parameters:

• message (required): Message text (supports Slack mrkdwn)
• channel (optional): Channel ID or name (uses default if not set)
• thread_ts (optional): Thread timestamp to reply in a thread
• urgency (optional): normal, important, or critical
• mention_user (optional): If true, @mentions the configured user

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)

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

Variable	Required	Description
SLACK_BOT_TOKEN	Yes	Bot token from Slack app (xoxb-...)
SLACK_DEFAULT_CHANNEL	No	Default channel for notifications

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