Slack MCP Server

What is Slack MCP Server?

Slack MCP Server is a Model Context Protocol (MCP) server for Slack Workspaces. It supports Stdio, SSE, and HTTP transports, proxy settings, DMs, Group DMs, smart history fetch (by date or count), and works via OAuth or in stealth mode without requiring additional permissions or bot installations.

How to use Slack MCP Server?

Install and configure the server with environment variables for transport, proxy, and authentication mode. Enable tools like conversations_add_message and reactions_add via environment variables (SLACK_MCP_ADD_MESSAGE_TOOL, SLACK_MCP_REACTION_TOOL) for safety. Use any MCP client that supports Stdio, SSE, or HTTP transports.

Key features of Slack MCP Server

• Stealth and OAuth authentication modes.
• Enterprise Slack workspace support.
• Channel and thread history with #Name and @Lookup.
• Smart history fetch by date range or message count.
• Unread messages across channels with priority sorting.
• Search messages with multiple filters (date, user, content).
• Safe, configurable message posting and reactions.

Use cases of Slack MCP Server

• Fetch and analyze channel or thread messages in Slack.
• Search messages across channels and DMs with date and user filters.
• Retrieve unread messages with @mention filtering.
• Add or remove emoji reactions to messages.
• Post messages to channels or threads (when enabled).

FAQ from Slack MCP Server

Which authentication modes are supported?

The server supports stealth mode (no additional permissions or bot installation) and OAuth mode (secure tokens without browser extraction).

Are bot tokens supported?

Bot tokens (xoxb-*) are supported for most tools, but conversations_search_messages is not available when using bot tokens because the search.messages API is not accessible.

How do I enable the message posting tool?

Set the SLACK_MCP_ADD_MESSAGE_TOOL environment variable. If set to a comma-separated list of channel IDs, posting is allowed only in those channels.

What transports are supported?

Stdio, SSE, and HTTP transports are supported, with optional proxy support for outgoing requests.

Where does data live?

User and channel data is cached locally for faster access. Authentication tokens or cookies are used as configured. No external data storage is described.