Slack MCP Server

A Model Context Protocol (MCP) server that provides Slack integration capabilities. This server follows clean architecture principles with proper separation of concerns.

Features

• List Channels: Get all public channels in your workspace with pagination support

• Post Messages: Send messages to specific channels

• Reply to Threads: Reply to existing message threads

• Add Reactions: Add emoji reactions to messages

• Get Channel History: Retrieve recent messages from channels

• Get Thread Replies: Get all replies in a message thread

• Parse Slack URLs: Automatically extract thread details from Slack URLs

Architecture

This project follows clean architecture principles:

src/
├── core/                 # Domain layer
│   ├── interfaces/      # Interfaces and contracts
│   └── types/          # Type definitions
├── application/         # Application layer
│   ├── services/       # Business logic services
│   └── usecases/       # Use case implementations
├── infrastructure/     # Infrastructure layer
│   ├── server/         # Mcp server configuration
│   ├── clients/        # External API clients
│   └── storage/        # Storage implementations
├── presentation/       # Presentation layer
│   └── routes/         # API routes (if needed)
└── config/             # Configuration and dependency injection

Setup

1. Slack App Configuration

First, create a Slack App and configure the required permissions:

1. Go to https://api.slack.com/apps

2. Create a new app or select existing one

3. Navigate to OAuth & Permissions → Bot Token Scopes

4. Add the following permissions:

   channels:read       - List channels
   channels:history    - Read public channel messages
   groups:history      - Read private channel/group messages
   chat:write         - Send messages
   reactions:write    - Add emoji reactions

5. Click Install App to Workspace

6. Copy the Bot User OAuth Token (starts with xoxb-)

2. Project Setup

1. Install dependencies:

   npm install

2. Build the project:

   npm run build

3. Run the server:

   npm start

3. MCP Configuration

Add to your MCP client configuration (e.g., Cursor):

{
  "slack-mcp": {
    "url": "http://localhost:3001/sse",
    "env": {
      "SLACK_TOKEN": "xoxb-your-bot-token-here"
    }
  }
}

Development

• Development mode: npm run dev

• Inspector mode: npm run inspector

• Clean build: npm run clean && npm run build

Token Management

All tools require a token parameter (Slack Bot Token). The token is passed directly to each tool call, ensuring secure and flexible authentication.

Example usage:

await slack_list_channels({
  limit: 50,
  token: "xoxb-your-bot-token-here",
});

Available Tools

slack_list_channels

List public channels in the workspace with pagination.

Parameters:

• limit (optional): Maximum number of channels to return (default 100, max 200)

• cursor (optional): Pagination cursor for next page of results

• token: Slack bot token (required)

slack_post_message

Post a new message to a Slack channel.

Parameters:

• channel_id: The ID of the channel to post to

• text: The message text to post

• token: Slack bot token (required)

slack_reply_to_thread

Reply to a specific message thread in Slack.

Parameters:

• channel_id: The ID of the channel containing the thread

• thread_ts: The timestamp of the parent message

• text: The reply text

• token: Slack bot token (required)

slack_add_reaction

Add a reaction emoji to a message.

Parameters:

• channel_id: The ID of the channel containing the message

• timestamp: The timestamp of the message to react to

• reaction: The name of the emoji reaction (without ::)

• token: Slack bot token (required)

slack_get_channel_history

Get recent messages from a channel.

Parameters:

• channel_id: The ID of the channel

• limit (optional): Number of messages to retrieve (default 10)

• token: Slack bot token (required)

slack_get_thread_replies

Get all replies in a message thread.

Parameters:

• channel_id: The ID of the channel containing the thread

• thread_ts: The timestamp of the parent message

• token: Slack bot token (required)

slack_parse_url

Parse a Slack URL and automatically extract thread/message details.

Parameters:

• url: Slack URL (e.g., https://workspace.slack.com/archives/CHANNEL_ID/pTIMESTAMP)

• token: Slack bot token (required)

Example:

await slack_parse_url({
  url: "https://workspace.slack.com/archives/CHANNEL_ID/pTIMESTAMP",
  token: "xoxb-your-bot-token-here",
});

This tool automatically:

• Parses the URL to extract workspace, channel ID, and message timestamp

• Fetches channel history

• Retrieves thread replies if available

• Returns formatted message details

License

MIT