What it does
This MCP server integrates Slack workspaces into Claude conversations, providing access to channel and thread messages, unread alerts, and message search. It supports Stdio, SSE, and HTTP transports with optional proxy routing. The server can operate in stealth mode—running without additional workspace admin permissions or bot installations—or via OAuth tokens. Core capabilities include fetching message history by date range or count, retrieving thread replies, aggregating unread messages with priority sorting (@mentions first), and searching across conversations. Message posting is available but disabled by default for safety.
Who it's for
Backend engineers and DevOps teams building internal Slack integrations, support coordinators analyzing conversation history, and developers who want Claude to access Slack context without requesting new workspace permissions. Teams running workflows that depend on structured access to conversation data.
Common use cases
- Retrieve channel or thread history by date (e.g., "messages from #incidents in the last 7 days") to ground Claude's analysis
- Search Slack conversations for specific topics or user mentions across multiple channels
- Aggregate and prioritize unread messages to surface high-priority discussions and @mentions
- Fetch thread replies to resolve questions embedded in conversation threads
- Post bot responses or analytical summaries to designated channels (when enabled via environment variable)
Setup pitfalls
- Message posting is disabled by default; enable via
SLACK_MCP_ADD_MESSAGE_TOOLenvironment variable and restrict to specific channel IDs if needed - Both stealth and OAuth modes require a valid Slack workspace token—treat this as a credential and store it securely
- Stealth mode bypasses workspace admin approval but still requires appropriate API token scopes; verify token permissions match intended usage
- Free Slack workspaces have a 90-day message history limit; requests beyond available history return partial results