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iskifogl

Slack MCP Server

by iskifogl
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TypeScript
Remote

Slack MCP Server

A Model Context Protocol (MCP) server for Slack API integration. This server allows AI assistants to interact with Slack workspaces through OAuth 2.0 authenticated user tokens.

Features

  • Channel Operations: List channels, get channel info, get channel members

  • Message Operations: Read messages, send messages, reply to threads, search messages

  • User Operations: List users, get user info, get user profiles

  • File Operations: List files, get file info, upload files

  • Reaction Operations: Add/remove reactions, get message reactions

Prerequisites

  • Node.js 18+

  • A Slack App with OAuth 2.0 configured

  • User token (xoxp-...) with appropriate scopes

Installation

npm install npm run build

Slack App Setup

1. Create a Slack App

  1. Go to api.slack.com/apps

  2. Click "Create New App" → "From scratch"

  3. Enter app name and select workspace

2. Configure OAuth Scopes

Add these User Token Scopes under "OAuth & Permissions":

channels:read # List channels channels:history # Read channel messages groups:read # List private channels groups:history # Read private channel messages im:read # List direct messages im:history # Read direct messages mpim:read # List group DMs mpim:history # Read group DMs chat:write # Send messages users:read # List users users.profile:read # Read user profiles files:read # List files files:write # Upload files reactions:read # Read reactions reactions:write # Add/remove reactions search:read # Search messages

3. Configure Redirect URI

Add your platform's callback URL under "OAuth & Permissions" → "Redirect URLs":

https://your-platform.com/oauth/slack/callback

4. Get Client Credentials

Note down your:

  • Client ID

  • Client Secret

Environment Variables

The MCP server reads credentials from environment variables:

# Required SLACK_ACCESS_TOKEN=xoxp-your-user-token # Optional SLACK_TEAM_ID=T0123456789

OAuth 2.0 Flow (Platform Implementation)

Step 1: Redirect User to Slack Authorization

const SLACK_CLIENT_ID = 'your-client-id'; const REDIRECT_URI = 'https://your-platform.com/oauth/slack/callback'; const SCOPES = 'channels:read,channels:history,chat:write,users:read,files:read,files:write,reactions:read,reactions:write,search:read,groups:read,groups:history,im:read,im:history,mpim:read,mpim:history,users.profile:read'; const authUrl = `https://slack.com/oauth/v2/authorize?client_id=${SLACK_CLIENT_ID}&user_scope=${SCOPES}&redirect_uri=${encodeURIComponent(REDIRECT_URI)}&state=${generateRandomState()}`; // Redirect user to authUrl

Step 2: Handle OAuth Callback

// In your callback handler app.get('/oauth/slack/callback', async (req, res) => { const { code, state } = req.query; // Verify state to prevent CSRF if (!verifyState(state)) { return res.status(400).send('Invalid state'); } // Exchange code for token const response = await fetch('https://slack.com/api/oauth.v2.access', { method: 'POST', headers: { 'Content-Type': 'application/x-www-form-urlencoded', }, body: new URLSearchParams({ client_id: SLACK_CLIENT_ID, client_secret: SLACK_CLIENT_SECRET, code, redirect_uri: REDIRECT_URI, }), }); const data = await response.json(); if (data.ok) { // Save user token to your database const userToken = data.authed_user.access_token; // xoxp-... const userId = data.authed_user.id; const teamId = data.team.id; await db.saveSlackToken(currentUserId, { token: userToken, slackUserId: userId, teamId: teamId, }); res.redirect('/success'); } else { res.status(400).send(`OAuth error: ${data.error}`); } });

Step 3: Start MCP Server with User Token

// When starting the MCP server for a user, inject their token as env var const userSlackToken = await db.getSlackToken(currentUserId); const mcpProcess = spawn('node', ['/path/to/slack-mcp/dist/index.js'], { env: { ...process.env, SLACK_ACCESS_TOKEN: userSlackToken, }, });

MCP Configuration

Add to your Claude Code configuration (~/.claude/claude_desktop_config.json):

{ "mcpServers": { "slack": { "command": "node", "args": ["/path/to/slack-mcp/dist/index.js"], "env": { "SLACK_ACCESS_TOKEN": "xoxp-your-token" } } } }

Available Tools

Channel Tools

Tool

Description

slack_list_channels

List all accessible channels

slack_get_channel_info

Get channel details

slack_get_channel_members

Get channel member list

Message Tools

Tool

Description

slack_get_messages

Get messages from a channel

slack_get_thread_replies

Get replies in a thread

slack_send_message

Send a message to a channel

slack_reply_to_thread

Reply to a thread

slack_search_messages

Search messages (requires user token)

User Tools

Tool

Description

slack_list_users

List workspace users

slack_get_user_info

Get user details

slack_get_user_profile

Get user profile

File Tools

Tool

Description

slack_list_files

List shared files

slack_get_file_info

Get file details

slack_upload_file

Upload a file

Reaction Tools

Tool

Description

slack_add_reaction

Add emoji reaction

slack_remove_reaction

Remove emoji reaction

slack_get_reactions

Get message reactions

Example Usage

List Channels

{ "tool": "slack_list_channels", "arguments": { "types": "public_channel,private_channel", "limit": 50 } }

Send Message

{ "tool": "slack_send_message", "arguments": { "channel_id": "C1234567890", "text": "Hello from MCP!" } }

Search Messages

{ "tool": "slack_search_messages", "arguments": { "query": "from:@user in:#channel important", "count": 20 } }

Error Handling

The server returns structured error responses:

{ "error": "Slack API Error (invalid_auth): Invalid authentication token." }

Common error codes:

  • invalid_auth: Token is invalid

  • token_revoked: Token has been revoked

  • missing_scope: Token lacks required scope

  • channel_not_found: Channel doesn't exist

  • ratelimited: Rate limit exceeded

Security Considerations

  • Never expose user tokens in client-side code

  • Store tokens securely in your database (encrypted)

  • Use HTTPS for all OAuth redirects

  • Validate state parameter to prevent CSRF

  • Rotate tokens periodically using refresh tokens

  • Request only necessary scopes

License

MIT

This server cannot be installed

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security - not tested
F
license - not found
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quality - not tested

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