Slack MCP Server

A read-only MCP (Model Context Protocol) server for Slack with OAuth 2.1 authentication.

Demo

https://github.com/user-attachments/assets/211bd428-209f-461a-b9a1-9cc85fd7c438

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

Related MCP server: slack-readonly-mcp

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 server.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

Authentication happens automatically via OAuth 2.1 when your MCP client first connects. Your client will open a browser window for Slack authorization — approve access and you're ready to go.

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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