@sigmacomputing/slack-mcp-server

What it does

This is a read-only MCP server for the Sigma Slack workspace, designed to be used from Cursor IDE or other MCP clients. It provides tools to list and join channels, read message history and threads, search messages and files across the workspace, download file attachments, view reactions and user profiles, and browse pins and bookmarks. The server is a fork of the Zencoder Slack MCP server, customized for Sigma with added support for file downloads, full-text search, and reaction management.

Who it's for

Sigma employees and workspace members who want to reference Slack discussions, search for shared files, and look up team information without leaving their editor or IDE.

Common use cases

• Search message history across public channels to find past decisions or context on a codebase area.
• Download files shared in Slack (code snippets, documents, logs) directly from your editor.
• Review threaded discussions and context around design decisions or incident reports.
• Look up user profiles and workspace member information during code review or collaboration.
• Fetch pins and bookmarks from channels to access frequently referenced resources.

Setup pitfalls

• Authentication requires valid Slack workspace credentials for Sigma; the server is scoped to the Sigma workspace only.
• The bot must join a channel before reading its message history; use slack_join_channel first for private or restricted channels.
• File downloads are capped at 10 MB; binary files are saved to a local temp directory while text files are returned as strings.
• This server is read-only by design — no message posting, editing, or thread replies are supported.