Let your agent into Slack — no bot install, no scopes

What it does It exposes a Slack workspace to MCP clients as tools: channel and thread history, message search, channel and user lookup, unread triage, and opt-in posting and reactions. It speaks Stdio, SSE and HTTP, supports proxies, and handles Enterprise and GovSlack setups. Channels are addressable as #general or @username instead of raw Cxxxxxxxxxx IDs, saving the agent a lookup round-trip. The README bills itself as ’the most powerful MCP Slack server’, which is quite a claim — but the tool surface is genuinely broad.

The interesting bit The signature trick is stealth mode: instead of a scoped bot token, the server can run on your existing browser session tokens (xoxc/xoxd) — no app to install, no scopes to request, no admin to convince. The second trick runs the other direction: every write tool ships disabled, and posting or reactions can be scoped to specific channels only. A sensible leash for something that types on your behalf.

Key highlights

• Smart History paginates by time window (1d, 7d, 90d) or message count, not just opaque cursors.
• Unread messages arrive pre-sorted — DMs first, then partner channels, then internal — with @mention filtering and mark-as-read.
• Search filters by channel, user and date, and resolves a pasted Slack message URL to that exact message.
• User details are embedded in fetched messages, so the agent knows who said what without extra calls.
• Users and channels are cached for faster lookups.

Caveats

• Message search is unavailable with bot tokens (xoxb-*) — Slack’s search.messages API simply doesn’t permit it.
• With OAuth tokens, users_search only pattern-matches the local cache; real-time search requires session tokens.
• Stealth mode rides on browser session tokens, which is unofficial territory. The README winks at it; your security team may not.

Verdict If you want an agent that can actually catch up on Slack — DMs, threads, the unread pile — this is one of the more complete tool surfaces around. If your workspace has opinions about session tokens, run it in OAuth mode and accept the search limits.