Slack MCP Server

About

The Slack MCP server (built by Ivan Korotovsky) connects AI assistants like Claude, Cursor, and Windsurf directly to Slack workspaces, enabling conversational access to your team communication channels without requiring workspace admin approval for a bot install. Its standout feature is a "no permission" stealth mode — it authenticates using your own personal Slack session tokens (xoxc/xoxd, or a stored browser session) rather than requiring a Slack App with OAuth scopes, so it works even in locked-down workspaces where you cannot create bots. It also supports full OAuth Bot Token auth and Enterprise/GovSlack deployments for teams that prefer a conventional app install. Tools exposed include reading channel and DM/group-DM history with smart pagination, searching messages across the workspace, posting messages and thread replies, listing channels and users, and adding reactions. Common use cases include automating standups by posting summaries directly to team channels, searching past Slack conversations to surface decisions or context, monitoring specific channels for keywords or alerts, and drafting replies to thread discussions — all from natural-language prompts. Supports both Stdio and SSE transports plus proxy configuration for corporate networks. Install with: `npx slack-mcp-server@latest --transport stdio`. A separate official-style integration exists from Zencoder (@zencoderai/slack-mcp-server) for teams that prefer standard Bot Token OAuth over session-token auth. Compatible with Claude Desktop, Cursor, VS Code, Windsurf, and Cline.

Installation

npx -y slack-mcp-server@latest --transport stdio

Setting up the Slack MCP server

1. 1.Pick a token type first — it decides what works

   The server takes one of three: xoxp (user OAuth), xoxb (bot, most limited), or the xoxc + xoxd browser pair. Bot tokens cannot call Slack's search.messages API, so conversations_search_messages is out. The saved-items tools and @mention filtering in unreads need browser tokens specifically, and conversations_unreads falls back to a slower path on standard OAuth tokens.

2. 2.Extract xoxc and xoxd, if you are going the browser-session route

   Open Slack in a browser, open developer tools, and in the console type "allow pasting" and press enter before pasting the snippet below — the value returned starts with xoxc-. Then switch to the Application tab, open Cookies, find the cookie named `d`, and copy its value; that is the xoxd token. Treat both as passwords.

   browser console

   JSON.parse(localStorage.localConfig_v2).teams[document.location.pathname.match(/^\/client\/([A-Z0-9]+)/)[1]].token

3. 3.Add the server to your client

   The published npm package is slack-mcp-server; there is also a Docker image at ghcr.io/korotovsky/slack-mcp-server if you would rather not run it through npx. Stdio, SSE and HTTP transports are all supported — for the network transports bind with SLACK_MCP_HOST (default 127.0.0.1) and SLACK_MCP_PORT (default 13080), and set SLACK_MCP_API_KEY as the bearer token, since an unauthenticated Slack bridge on a shared host is an open door.

   claude_desktop_config.json

   {
     "mcpServers": {
       "slack": {
         "command": "npx",
         "args": ["-y", "slack-mcp-server@latest", "--transport", "stdio"],
         "env": {
           "SLACK_MCP_XOXC_TOKEN": "xoxc-...",
           "SLACK_MCP_XOXD_TOKEN": "xoxd-..."
         }
       }
     }
   }

4. 4.Let the caches build, or lose channel lookup by name

   The server keeps a users cache and a channels cache, at SLACK_MCP_USERS_CACHE and SLACK_MCP_CHANNELS_CACHE. With neither, message history arrives without user context. With only the channels cache, you can address channels by name but user enrichment is missing; with only the users cache, "#engineering" will not resolve and you are back to raw channel IDs. Both present is the intended state, and the first run is the one that populates them.

5. 5.Decide, explicitly, whether it may write

   Posting is disabled by default. SLACK_MCP_ADD_MESSAGE_TOOL takes "true" to allow every channel, a comma-separated list of channel IDs to allow only those, or a "!" prefix on an ID to allow everything except it — a per-channel allowlist is the setting most teams actually want. Reactions and read-marking are gated separately behind SLACK_MCP_REACTION_TOOL and SLACK_MCP_MARK_TOOL.

   env

   "SLACK_MCP_ADD_MESSAGE_TOOL": "C08XXXXXXXX,C09YYYYYYYY"

The 18 tools

Everything in the first group is read-only and on by default. Everything that writes is off until you set the matching environment variable.

What people use it for

Which one should you use?

Categories

Works With

Frequently Asked Questions

Related Guides