Slack MCP Server with SSE Transport

A Model Context Protocol (MCP) server that provides Slack API integration using Server-Sent Events (SSE) transport. This server allows AI assistants to interact with Slack workspaces through a simple HTTP-based interface.

Features

- SSE Transport: Uses Server-Sent Events (SSE) instead of stdio, enabling communication over HTTP/HTTPS
- Slack API Integration: Provides access to essential Slack API functionality
- Simple Web Interface: Includes a basic web UI and health check endpoint
- Docker Support: Fully containerized with Docker for easy deployment
- TypeScript Implementation: Built with TypeScript for type safety and better developer experience
- Cross-Platform Compatibility: Works with any MCP client that supports SSE transport

Prerequisites

- Node.js 18 or higher
- Slack Bot Token with appropriate permissions
- Slack Team ID
- Docker (optional, for containerized deployment)

Environment Variables

| Variable | Description | Default |
|----------|-------------|---------|
| SLACK_BOT_TOKEN | Your Slack Bot User OAuth Token (starts with xoxb-) | Required |
| SLACK_TEAM_ID | Your Slack Workspace/Team ID | Required |
| PORT | Port on which the server will run | 3000 |

Setup Instructions

Obtaining Slack Bot Token and Team ID

1. Create a Slack App:
- Visit the Slack Apps page
- Click "Create New App"
- Choose "From scratch"
- Name your app and select your workspace

2. Configure Bot Token Scopes:
- Navigate to "OAuth & Permissions" in your app settings
- Add these scopes:
- channels:history - View messages and other content in public channels
- channels:read - View basic channel information
- chat:write - Send messages as the app
- reactions:write - Add emoji reactions to messages
- users:read - View users and their basic information

3. Install App to Workspace:
- Click "Install to Workspace" and authorize the app
- Save the "Bot User OAuth Token" that starts with xoxb-

4. Get your Team ID:
- Open Slack in a web browser
- Once logged in, check the URL in your browser
- The URL will be in a format like: https://app.slack.com/client/T01234567/...
- Your Team ID is the string beginning with T (e.g., T01234567)

Local Development

1. Clone the repository
2. Install dependencies:

   npm install

   

   SLACK_BOT_TOKEN=xoxb-your-slack-bot-token

   SLACK_TEAM_ID=your-slack-team-id

   PORT=3000

   

   npm run build

   

   npm start

   

For development with automatic reloading:

npm run dev

Docker Deployment

Using Docker Compose (Recommended)

1. Create a .env file with your Slack credentials as shown above
2. Build and run the container:

   docker compose up --build

   

Using Pre-built Image

docker run -p 3000:3000 \
  -e SLACK_BOT_TOKEN=xoxb-your-slack-bot-token \
  -e SLACK_TEAM_ID=your-slack-team-id \
  ghcr.io/dvelopment/slack-mcp-server-sse:latest

For more detailed Docker instructions, including publishing to GitHub Container Registry, see DOCKER.md.

Server Endpoints

- SSE Endpoint: /sse - Connect to this endpoint to receive SSE events
- Health Check: /health - Simple health check endpoint (returns {"status":"ok"})
- Home Page: / - Simple HTML page with information about the server

Available Slack API Tools

| Tool Name | Description | Required Parameters |
|-----------|-------------|---------------------|
| slack_list_channels | List public channels in the workspace with pagination | None (optional: limit, cursor) |
| slack_post_message | Post a new message to a Slack channel | channel_id, text |
| slack_reply_to_thread | Reply to a specific message thread in Slack | channel_id, thread_ts, text |
| slack_add_reaction | Add a reaction emoji to a message | channel_id, timestamp, reaction |
| slack_get_channel_history | Get recent messages from a channel | channel_id (optional: limit) |
| slack_get_thread_replies | Get all replies in a message thread | channel_id, thread_ts |
| slack_get_users | Get a list of all users in the workspace | None (optional: cursor, limit) |
| slack_get_user_profile | Get detailed profile information for a specific user | user_id |

Connecting to the Server

Node.js Client Example

// Replace with your server URL
const SERVER_URL = 'http://localhost:3000/sse';
// Create EventSource to connect to the SSE endpoint

const eventSource = new EventSource(SERVER_URL);
// Handle connection open

eventSource.onopen = () => {

  console.log('Connected to SSE server');

};
// Handle messages

eventSource.onmessage = (event) => {

  console.log('Received message:', event.data);

  try {

    const data = JSON.parse(event.data);

    console.log('Parsed data:', data);

  } catch (error) {

    console.log('Raw message (not JSON):', event.data);

  }

};
// Handle errors

eventSource.onerror = (error) => {

  console.error('SSE connection error:', error);

  eventSource.close();

};

See the examples directory for complete client examples:
- examples/client.js - Node.js client example
- examples/browser-client.html - Browser client example

Using with Claude MCP Wrapper

To use this server with the Claude MCP wrapper:

claude_mcp_wrapper.sh -y docker run -i --rm -e SLACK_BOT_TOKEN -e SLACK_TEAM_ID mcp/slack

Or for an SSE-based connection:

claude_mcp_wrapper.sh -y http://localhost:3000/sse

License

MIT