Slack MCP Server

What korotovsky/slack-mcp-server does

The korotovsky/slack-mcp-server MCP server exposes Slack workspace data and conversation actions through the Model Context Protocol. It can retrieve channel and direct-message history, read thread replies, search messages with multiple filters, list channels, and add messages when posting has been explicitly enabled.

Conversation references can use Slack IDs or lookup forms such as #general and @username_dm. Retrieved messages may include embedded user information, making it possible to associate activity with Slack users without a separate lookup for every result. The server also supports direct messages, group direct messages, private channels, and public channels where the relevant Slack access is available.

How it works

The server supports Stdio, SSE, and HTTP transports, so the MCP client determines how it is connected. Outgoing requests can be routed through a proxy. Workspace access can use OAuth tokens or a stealth mode that does not require additional permissions or a bot installation, according to the project documentation. Enterprise Slack workspace setups are also supported.

History requests accept a channel ID or supported name, then return a pagination cursor when more results are available. Limits can be expressed as a time range, such as a day or week, or as a message count. Thread retrieval uses a channel and message timestamp. Search can cover channels, DMs, and group DMs, with filters for dates, users, channels, message text, and thread-only results.

Setup and configuration

The korotovsky/slack-mcp-server MCP server can be connected through any MCP client that supports one of its documented transports.

Message posting is a deliberate opt-in. Set SLACK_MCP_ADD_MESSAGE_TOOL to enable the conversations_add_message tool. If its value is a comma-separated list of channel IDs, posting is restricted to those channels; otherwise, the documentation describes the variable as the switch for enabling the tool. Messages can be sent as plain text or Markdown, either to a conversation or to a thread.

Tools and capabilities

Documented tools include:

• conversations_history for channel or DM history with date, count, activity-message, and cursor controls.
• conversations_replies for paginated thread contents.
• conversations_search_messages for text, URL, user, date, channel, DM, and thread filters.
• conversations_add_message for optional channel, DM, or thread posting.
• channels_list for retrieving channel listings.

The server also describes smart unread-message retrieval with priority ordering, mention filtering, and mark-as-read support. User and channel caches can improve repeated lookups. User details exposed by the listing include Slack ID, username, real name, display name, email, title, and a cached DM channel ID when available.

Limitations and notes

Search is unavailable when the connection uses a Slack bot token beginning with xoxb-*, because that token type cannot use Slack’s message-search API. History limits may also be constrained by Slack’s available history and the applicable free-tier range described by the project.

Posting is disabled by default and should remain restricted unless an agent is intended to send messages. Access to private channels, DMs, and enterprise workspaces depends on the selected Slack access method and workspace configuration.