Slack MCP

MCP server that gives AI agents access to your Slack workspaces using session tokens. No OAuth apps, no bot permissions, no admin approval required.

Beyond reading and writing messages, it accumulates a durable picture of the workspace — every channel and user's state over time, departures kept as dated tombstones — and synthesizes a relationship graph from it on demand: estate view='about' person='X' answers "tell me about X" with their footprint, circle, and a ranked reading plan. The graph is never stored; it is computed per query from two small local ledgers that hold no message content (design note).

How it works

Slack MCP uses your existing browser session tokens (xoxc/xoxd) to interact with Slack on your behalf. It reads stealthily by default — only the mark-read tool triggers read receipts. Everything else is invisible to other users.

Token extraction is built into the binary. If you're logged into Slack in Chrome or Firefox, the setup flow can extract tokens automatically — no copy-pasting from DevTools.

Related MCP server: slack-mpm

Prerequisites

You need an active Slack session in your browser. Log into your workspace at app.slack.com in Chrome, Chromium, Edge, or Firefox before running setup.

Install

Claude Code

claude mcp add slack-mcp -- npx -y @aaronsb/slack-mcp

Then ask Claude to run the auth tool. It will guide you through browser selection, profile selection, and automatic token extraction.

Claude Desktop

Download the .mcpb file for your platform from the latest release:

Open the file (double-click or drag into Claude Desktop). When prompted for tokens, you can either:

• Leave them blank and use the auth tool after connecting

• Paste tokens if you already have them

Standalone binary

Download the binary for your platform from releases, then:

# Extract tokens from your browser (interactive)
./slack-mcp setup

# Run as MCP server (stdio, default)
./slack-mcp

# Run as MCP server (SSE, for remote/shared access)
./slack-mcp --transport sse

npm (global)

npm install -g @aaronsb/slack-mcp
slack-mcp setup

Token setup

There are three ways to get your Slack tokens, from easiest to most manual:

Automatic (Chrome/Edge)

The auth MCP tool or slack-mcp setup CLI command will:

1. Detect your installed browsers

2. Let you pick which browser and profile has Slack

3. Open the browser, navigate to Slack, and extract tokens via Chrome DevTools Protocol

4. Validate and save them

Requires Chrome to be fully closed before extraction — your tabs will restore when you reopen it.

Semi-automatic (Firefox)

The setup flow writes a temporary browser extension to a temp directory, then guides you to load it in Firefox via about:debugging. The extension extracts tokens and sends them to the local callback server. It's removed automatically when Firefox closes.

Manual

Run slack-mcp setup or use the auth tool — if no browser is detected or automatic extraction fails, it falls back to a localhost web page with step-by-step DevTools instructions.

You can also set tokens directly via environment variables:

export SLACK_MCP_XOXC_TOKEN="xoxc-..."
export SLACK_MCP_XOXD_TOKEN="xoxd-..."
./slack-mcp

Tools

Verb encodes effect, noun encodes domain, parameter encodes scope (ADR-009); the batch executor encodes composition, never effect, and admits only the read nouns (ADR-010). Every noun echoes its effective parameters and pages every capped list.

Privacy

• Stealth by default — reads never trigger read receipts; only mark-read does

• Channel names, not IDs — the AI never sees internal Slack identifiers

• Tokens stay local — stored in ~/.config/slack-mcp/config.json with 0600 permissions

• Ledgers hold no message content — the durable estate ledger stores entity facts (names, lifecycle, tombstones); the attention ledger stores {user, conversation, day} encounters with a 90-day window; both live under XDG with 0600, and deleting them deletes the graph

• Hour-level activity is recorded only for you — colleagues bucket by day, by design

• No network traffic except Slack — the binary connects only to slack.com/api/*

• No browser downloads — uses your installed browser, never fetches binaries from CDNs

Development

make build          # Build for current platform
make test           # Run tests
make build-all-platforms  # Cross-compile (6 platforms)
make release TAG=v2.1.1   # Tag and push (CI handles the rest)

License

MIT