Slack MCP Server

A read-only MCP (Model Context Protocol) server for Slack with OAuth authentication and multi-user session support.

Demo

slack_mcp_demo.mp4

Available Tools

• slack_get_channel_messages - Retrieve messages from channels
• slack_get_thread_replies - Get conversation thread replies
• slack_search_messages - Advanced message search with filters
• slack_get_users - List workspace users or get specific profiles
• slack_get_channels - List channels or get detailed info
• slack_get_oauth_url - Generate OAuth authorization URL

Quick Start

1. Create Slack App

1. Visit Slack API Apps and create a new app
2. Under App Credentials, copy your Client ID and Client Secret
3. Navigate to OAuth & Permissions and add these User Token Scopes: channels:history groups:history im:history mpim:history channels:read groups:read im:read mpim:read users:read users:read.email search:read
4. Add Redirect URL under OAuth & Permissions:
   • For local testing: Use an HTTPS proxy like ngrok (E.g: https://abc123.ngrok.io/oauth2callback). See local development setup below.
   • For production: https://your-domain.com/oauth2callback

2. Installation

uv sync

3. Local Development Setup (HTTPS Proxy)

Slack requires HTTPS for OAuth callbacks. For local development, use ngrok or a similar HTTPS proxy:

# Visit https://ngrok.com/ to download ngrok and start the proxy
ngrok http 8001

Copy the HTTPS forwarding URL (e.g., https://abc123.ngrok.io/oauth2callback) and add it as a Redirect URL in your Slack app settings.

4. Configuration

Set required environment variables:

export SLACK_CLIENT_ID="your_client_id"
export SLACK_CLIENT_SECRET="your_client_secret"
# Use https://your-domain.com for production.
export SLACK_MCP_BASE_URI="http://localhost"
# Use https://your-domain.com for production.
export SLACK_EXTERNAL_URL="https://abc123.ngrok.io"
# Optional, if you want to run the MCP server on a different port.
export SLACK_MCP_PORT=8001

5. Run the Server

uv run python main.py

The server will start on http://localhost:8001 by default. Make sure your ngrok proxy is running alongside it for OAuth to work.

6. Configure Your MCP Client

Add to your MCP client configuration (e.g. ~/.cursor/mcp.json for Cursor):

{
  "mcpServers": {
    "slack": { "url": "http://localhost:8001/mcp", "transport": "http" }
  }
}

7. Authenticate

Call slack_get_oauth_url() MCP tool to get the authorization URL, visit it in your browser, and approve access the first time you use the MCP server.

Deployment

For production deployment, you can run it inside docker:

docker build -t slack-mcp .
docker run -p 8001:8001 \
  -e SLACK_CLIENT_ID="your_client_id" \
  -e SLACK_CLIENT_SECRET="your_client_secret" \
  -e SLACK_MCP_BASE_URI="https://your-domain.com" \
  -e SLACK_EXTERNAL_URL="https://your-domain.com" \
  slack-mcp

Development

Run tests with uv run pytest.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

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