Slack MCP server

The MCP (Model Context Protocol) server for Slack provides a standardized interface for AI assistants to interact with Slack's API, enabling actions like posting messages, searching conversations, and managing reactions.

Installation

Install the package using npm:

npm install @ubie-oss/slack-mcp-server

Required Configuration

Set up the following environment variables:

• SLACK_BOT_TOKEN: Your Slack Bot User OAuth Token
• SLACK_USER_TOKEN: Your Slack User OAuth Token (needed for features like message search)
• SLACK_SAFE_SEARCH (optional): Set to true to automatically exclude private channels, DMs, and group DMs from search results

You can use a .env file to configure these variables:

SLACK_BOT_TOKEN=xoxb-your-bot-token
SLACK_USER_TOKEN=xoxp-your-user-token
SLACK_SAFE_SEARCH=true

Usage

Starting the Server

You can run the MCP server using either stdio transport (for local integration) or HTTP transport (for web applications).

Stdio Transport (Default)

npx @ubie-oss/slack-mcp-server

HTTP Transport

npx @ubie-oss/slack-mcp-server -port 3000

Command Line Options

• -port <number>: Start with HTTP transport on the specified port
• -h, --help: Display help information

Client Configuration

For Stdio Transport (e.g., Claude Desktop)

{
  "slack": {
    "command": "npx",
    "args": [
      "-y",
      "@ubie-oss/slack-mcp-server"
    ],
    "env": {
      "NPM_CONFIG_//npm.pkg.github.com/:_authToken": "<your-github-pat>",
      "SLACK_BOT_TOKEN": "<your-bot-token>",
      "SLACK_USER_TOKEN": "<your-user-token>",
      "SLACK_SAFE_SEARCH": "true"
    }
  }
}

For HTTP Transport (Web Applications)

Start the server:

SLACK_BOT_TOKEN=<your-bot-token> SLACK_USER_TOKEN=<your-user-token> npx @ubie-oss/slack-mcp-server -port 3000

Then connect to: http://localhost:3000/mcp

Available Tools

Channel Management

• slack_list_channels: List public channels in the workspace with pagination
• slack_get_channel_history: Retrieve recent messages from a channel

Messaging

• slack_post_message: Post a new message to a Slack channel
• slack_reply_to_thread: Reply to a specific message thread
• slack_get_thread_replies: Get all replies in a message thread

User Information

• slack_get_users: Get basic profile information for all workspace users
• slack_get_user_profiles: Retrieve multiple users' profile information in bulk

Interactions

• slack_add_reaction: Add a reaction emoji to a message

Search

• slack_search_messages: Search for messages with filters:
  • Basic query search
  • Location filters: in_channel
  • User filters: from_user, with
  • Date filters: before, after, on, during
  • Content filters: has (emoji reactions), is (saved/thread)
  • Sorting options by relevance score or timestamp

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "slack" '{"command":"npx","args":["-y","@ubie-oss/slack-mcp-server"],"env":{"NPM_CONFIG_//npm.pkg.github.com/:_authToken":"<your-github-pat>","SLACK_BOT_TOKEN":"<your-bot-token>","SLACK_USER_TOKEN":"<your-user-token>"}}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "slack": {
            "command": "npx",
            "args": [
                "-y",
                "@ubie-oss/slack-mcp-server"
            ],
            "env": {
                "NPM_CONFIG_//npm.pkg.github.com/:_authToken": "<your-github-pat>",
                "SLACK_BOT_TOKEN": "<your-bot-token>",
                "SLACK_USER_TOKEN": "<your-user-token>"
            }
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "slack": {
            "command": "npx",
            "args": [
                "-y",
                "@ubie-oss/slack-mcp-server"
            ],
            "env": {
                "NPM_CONFIG_//npm.pkg.github.com/:_authToken": "<your-github-pat>",
                "SLACK_BOT_TOKEN": "<your-bot-token>",
                "SLACK_USER_TOKEN": "<your-user-token>"
            }
        }
    }
}

3. Restart Claude Desktop for the changes to take effect