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MCP Slack

Official registry Productivity

Secure read-only MCP server for Slack workspaces

Source code Documentation

What can you do with MCP Slack?

  • Mostly read: 15 of the 17 tools only read and publish readOnlyHint: true. The other two send a message and cancel a scheduled one; nothing edits or deletes existing content.
  • Secure: 6-layer security model (input validation, token handling, client hardening, output sanitization, runtime protection, supply chain security).
  • User OAuth Token: Uses xoxp- tokens for user-scoped access to your workspace.
  • No SDK dependency: Uses httpx directly for minimal, auditable HTTP calls.

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

PYPI package mcp-slack-crunchtools
Claude Code 
claude mcp add mcp-slack -- uvx mcp-slack-crunchtools==0.1.2
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "mcp-slack": {
            "command": "uvx",
            "args": [
                "mcp-slack-crunchtools==0.1.2"
            ]
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. mcp-slack-crunchtools
  2. Features
  3. Quick Start
  4. Setup
  5. Configuration
  6. Tools
  7. Security
  8. License

mcp-slack-crunchtools

Secure MCP server for Slack workspaces. Provides Claude Code (and other MCP clients) with read access to your Slack channels, messages, users, and files, and can send a message on your behalf.

Features

  • Mostly read: 15 of the 17 tools only read and publish readOnlyHint: true. The other two send a message and cancel a scheduled one; nothing edits or deletes existing content.
  • Secure: 6-layer security model (input validation, token handling, client hardening, output sanitization, runtime protection, supply chain security).
  • User OAuth Token: Uses xoxp- tokens for user-scoped access to your workspace.
  • No SDK dependency: Uses httpx directly for minimal, auditable HTTP calls.

Quick Start

claude mcp add mcp-slack-crunchtools \
    --env SLACK_USER_TOKEN=xoxp-your-token \
    -- uvx mcp-slack-crunchtools
Using Container
claude mcp add mcp-slack-crunchtools \
    --env SLACK_USER_TOKEN=xoxp-your-token \
    -- podman run -i --rm -e SLACK_USER_TOKEN quay.io/crunchtools/mcp-slack
Local Development
claude mcp add mcp-slack-crunchtools \
    --env SLACK_USER_TOKEN=xoxp-your-token \
    -- uv run mcp-slack-crunchtools

Setup

See CLAUDE.md for detailed instructions on creating a Slack app and obtaining a User OAuth Token.

Configuration

Authentication uses one of two mutually exclusive modes. The server picks cookie mode when both cookie variables are set, and token mode otherwise.

VariableRequiredDefaultDescription
SLACK_USER_TOKENtoken mode—User OAuth token (xoxp-...) from a Slack app installed in the workspace.
SLACK_COOKIE_TOKENcookie mode—Browser session token (xoxc-...). Must be paired with SLACK_COOKIE_D.
SLACK_COOKIE_Dcookie mode—Value of the d cookie (xoxd-...) from the same browser session. Sent as a Cookie: header alongside SLACK_COOKIE_TOKEN.
SLACK_ADD_MESSAGE_DELAYno3mHow far ahead outgoing messages are scheduled, giving you a window to cancel one. Duration string: 30s, 5m, 2h, or a bare integer for seconds. Set to 0, 0s, none, or false to disable scheduling and post immediately.
Which auth mode to use

Cookie mode is the working path for this deployment. Token mode requires a Slack app to be created and approved in the workspace; where that approval is not available, cookie mode is the only way to authenticate at all.

Cookie mode borrows an existing browser session rather than holding a credential issued to an application. That has consequences worth stating plainly:

  • Both values are live session credentials. Anything holding them can act as you in Slack, with your full access. Treat them exactly as you would your password.
  • They expire when the browser session does, so cookie mode needs periodic re-extraction. A sudden wave of auth failures usually means the session rotated, not that the server broke.
  • Slack does not issue these for programmatic use and can invalidate them at any time. Cookie mode is a workaround for the absence of an approved app, not a supported integration path.

Prefer SLACK_USER_TOKEN whenever a Slack app can actually be installed.

Tools

ToolDescription
slack_auth_testTest connection and get token owner info
slack_list_channelsList workspace channels
slack_get_channel_infoGet channel details
slack_get_channel_historyRead channel messages
slack_get_thread_repliesRead thread replies
slack_list_channel_membersList channel members
slack_search_messagesSearch messages
slack_get_reactionsGet message reactions
slack_list_reactionsList user's reactions
slack_list_starsList starred items
slack_get_user_infoGet user details
slack_list_usersList workspace members
slack_get_user_profileGet user profile
slack_list_filesList files (metadata only)
slack_get_file_infoGet file metadata
slack_send_messageSchedule a message SLACK_ADD_MESSAGE_DELAY ahead, or post it immediately when the delay is 0 (write)
slack_cancel_scheduled_messageCancel a scheduled message before it sends (write)

The two write tools need the chat:write scope in token mode.

Security

See SECURITY.md for the full security design document.

License

AGPL-3.0-or-later

Frequently asked questions

What is MCP Slack?

Secure read-only MCP server for Slack workspaces

How do I install MCP Slack?

It runs on your machine. In Claude Code: claude mcp add mcp-slack -- uvx mcp-slack-crunchtools==0.1.2. For other clients, paste the JSON configuration from this page into their MCP settings.

Does MCP Slack need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is MCP Slack open source?

Yes. Its code is on GitHub under the AGPL-3.0 license.

Who maintains MCP Slack?

It is published by crunchtools. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.