Slack MCP Server

A Model Context Protocol (MCP) server for Slack integration, allowing Claude to interact with your Slack workspace. This server runs exclusively in Docker/Podman containers.

Features

• Send messages to channels or users
• Send replies to message threads
• Search for messages across the workspace
• List all channels in workspace
• Get channel message history
• Get replies from message threads
• List all users in workspace

Prerequisites

• Docker or Podman installed
• A Slack Bot Token (see Setup section)

Setup

1. Create a Slack App

1. Go to https://api.slack.com/apps
2. Click "Create New App" → "From scratch"
3. Give it a name and select your workspace

2. Configure Bot Token Scopes

Go to OAuth & Permissions and add these Bot Token Scopes:

• channels:read
• chat:write
• users:read
• channels:history
• groups:read
• groups:history

3. Install the App

1. Click "Install to Workspace"
2. Copy the Bot User OAuth Token (starts with xoxb-)

4. Set Up Environment Variable

Create a .env file in the project root:

SLACK_BOT_TOKEN=xoxb-your-bot-token-here

Running with Docker

Build the Image

docker build -t slack-mcp-server .

Run the Container

docker run -i \
  -e SLACK_BOT_TOKEN=xoxb-your-bot-token-here \
  slack-mcp-server

Using docker-compose

# Set your token in .env file first
docker-compose up

Running with Podman

Build the Image

podman build -t slack-mcp-server .

Run the Container

podman run -i \
  -e SLACK_BOT_TOKEN=xoxb-your-bot-token-here \
  slack-mcp-server

Using podman-compose

# Set your token in .env file first
podman-compose up

Configuration with Claude Code

Add this to your Claude Code MCP settings file:

Docker Configuration

{
  "mcpServers": {
    "slack": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "SLACK_BOT_TOKEN=xoxb-your-actual-bot-token-from-step-3",
        "slack-mcp-server"
      ]
    }
  }
}

Podman Configuration

{
  "mcpServers": {
    "slack": {
      "command": "podman",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "SLACK_BOT_TOKEN=xoxb-your-actual-bot-token-from-step-3",
        "slack-mcp-server"
      ]
    }
  }
}

Alternative: Using Environment File

{
  "mcpServers": {
    "slack": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "--env-file",
        "/absolute/path/to/.env",
        "slack-mcp-server"
      ]
    }
  }
}

Available Tools

The server communicates via stdio and provides these tools:

• send_message: Send a message to a channel or user
• send_thread_reply: Send a reply to a message thread
• search_messages: Search for messages across the workspace (supports Slack search syntax)
• list_channels: List all workspace channels
• get_channel_history: Get recent messages from a channel
• get_thread_replies: Get all replies from a message thread
• list_users: List all workspace users

Search Examples

The search_messages tool supports Slack's powerful search syntax:

• "error message" - Search for exact phrase
• from:@username - Messages from specific user
• in:#channel - Messages in specific channel
• after:2024-01-01 - Messages after date
• has:link - Messages containing links
• Combine: from:@john in:#general error - Complex queries

Development

Build and Test Locally

# Build the image
docker build -t slack-mcp-server:dev .

# Run tests
docker run --rm slack-mcp-server:dev npm test

Shell Access for Debugging

docker run -it --rm \
  -e SLACK_BOT_TOKEN=xoxb-your-token \
  --entrypoint /bin/sh \
  slack-mcp-server

Security Features

• Multi-stage build for minimal image size
• Non-root user execution
• Read-only root filesystem
• No new privileges
• Resource limits configured in docker-compose
• Minimal Alpine Linux base image

Troubleshooting

Container exits immediately

Make sure you're running with -i (interactive) flag for stdin communication.

Token not found

Verify your SLACK_BOT_TOKEN is correctly set in the environment or .env file.

Permission errors

The container runs as a non-root user (nodejs). Ensure any mounted volumes have appropriate permissions.

License

MIT