Slack MCP Server 🔌 MCP server Open source

What it does

This community Slack MCP server, written in Go, lets an agent read and search your Slack workspace. It covers channels, threads, DMs, group DMs and unread messages, and it can post only if you allow it. For developers, it gives an agent the discussion behind a feature: it can pull a bug-report thread into context before fixing the bug, search for an earlier decision, or summarise what changed overnight. Slack Connect partner channels, Enterprise Grid and GovSlack are supported. Message history can be limited by date range or by message count, and user and channel lists are cached locally so lookups are quick. It is not an official Slack product.

Tools it gives your agent

• conversations_history, conversations_replies and conversations_unreads for reading channels, threads and unread items
• conversations_search_messages, with filters for channel, user and date
• channels_list, users_search and user-group list, create and update tools
• Off by default: conversations_add_message, reactions_add/reactions_remove, conversations_mark and attachment_get_data, each switched on by its own environment variable, and posting and reactions can be limited to specific channels

Works with

It runs locally over stdio, or as an SSE or HTTP server bound to 127.0.0.1 by default. You can install it with npx, Docker, a Claude Desktop extension or a Cursor installer. Other MCP clients should work too.

How to connect

The npx config from the project docs, using a user OAuth token:

{
  "mcpServers": {
    "slack": {
      "command": "npx",
      "args": [
        "-y",
        "slack-mcp-server@latest",
        "--transport",
        "stdio"
      ],
      "env": {
        "SLACK_MCP_XOXP_TOKEN": "xoxp-..."
      }
    }
  }
}

Cost and limits

It is free and MIT-licensed. You need a Slack workspace and one kind of token. Bot tokens only see channels the bot is invited to and cannot search. Some tools only work with browser session tokens.

Safety notes

"Stealth mode" uses xoxc and xoxd values copied from your logged-in browser session. That skips app installation and admin approval, may break your workspace's policies or Slack's terms, and gives the agent your full account access. Prefer a user OAuth token or a bot token. Keep posting disabled, or limit it to specific channels. When you expose SSE or HTTP, set SLACK_MCP_API_KEY. Slack messages are untrusted input and may contain prompt injection. The agent may also send private conversations to your model provider.