MCP Slack Server

A powerful multi-account Model Context Protocol (MCP) server for Slack that enables seamless workspace switching and persistent credential storage.

Features

• 🔄 Multi-Account Support: Switch between multiple Slack workspaces at runtime
• 🔐 Secure Credential Storage: Uses native OS keychains with encrypted file-based fallback
• ⚡ Fast Performance: <200ms startup time for 10+ workspaces
• 🛡️ Dual Storage System: Automatic fallback to encrypted file storage if keychain unavailable
• 🔍 Comprehensive Slack Tools: 40+ tools for messages, channels, users, files, and more
• 📁 Reliable Persistence: Accounts persist across Claude sessions
• ✨ Automatic Markdown Conversion: Converts common markdown formatting to Slack's mrkdwn format

Installation

Using Claude Desktop

claude mcp add slack -- npx @chinchillaenterprises/mcp-slack

Using Claude Code (Recommended)

# Install with user scope for persistence across sessions
claude mcp add slack -s user -- npx @chinchillaenterprises/mcp-slack

# Or with environment variables for default workspace
claude mcp add slack -s user -e DEFAULT_BOT_TOKEN=xoxb-YOUR-BOT-TOKEN -e DEFAULT_TEAM_ID=YOUR-TEAM-ID -- npx @chinchillaenterprises/mcp-slack

Manual Installation

npm install -g @chinchillaenterprises/mcp-slack

Configuration

Environment Variables

For the default workspace:

• DEFAULT_BOT_TOKEN: Slack bot token (xoxb-...)
• DEFAULT_USER_TOKEN: Slack user token (xoxp-...)
• DEFAULT_TEAM_ID: Slack team/workspace ID
• DEFAULT_ACCOUNT_NAME: Display name for the workspace

Usage

Account Management

The V3 architecture introduces powerful account management capabilities:

• list_accounts: View all configured workspaces
• switch_account: Change active workspace at runtime
• add_account: Add new workspace credentials
• remove_account: Remove workspace from configuration
• update_account: Update existing workspace credentials

Core Slack Tools

Messaging

• slack_send_message: Send messages to channels (with automatic markdown → Slack formatting)
• slack_send_formatted_message: Send rich Block Kit messages
• slack_edit_message: Edit existing messages
• slack_delete_message: Delete messages
• slack_schedule_message: Schedule messages for later
• slack_forward_message: Forward messages between channels

Channels & History

• slack_list_channels: List accessible channels
• slack_get_channel_history: Get recent messages
• slack_get_thread_replies: Get thread conversations

Search

• slack_search_messages: Search across workspace
• slack_search_by_user: Find messages from specific users
• slack_search_by_date_range: Search within date ranges
• slack_search_files: Search for shared files

Users & Teams

• slack_list_users: List workspace members
• slack_get_user_by_name: Find users by name
• slack_get_user_info: Get detailed user information
• slack_get_user_status: Check user status
• slack_get_user_profile: Get full profile details

Reactions & Pins

• slack_add_reaction: Add emoji reactions
• slack_bulk_react_messages: React to multiple messages
• slack_pin_message: Pin important messages
• slack_unpin_message: Unpin messages

Productivity

• slack_create_reminder: Set reminders
• slack_list_reminders: View active reminders
• slack_get_workspace_stats: Get workspace analytics

Automatic Markdown Conversion

The slack_send_message tool now automatically converts common markdown formatting to Slack's mrkdwn format:

• Bold: **text** → *text*
• Links: [text](url) → <url|text>
• Strikethrough: ~~text~~ → ~text~
• Headers: # Header → *Header*
• Lists: - item → • item

This means Claude can use standard markdown formatting and it will appear correctly in Slack without manual conversion.

Advanced Features

Persistent Storage

The server uses a dual-storage system for maximum reliability:

1. Primary Storage: Native OS keychain

   • macOS: Keychain Access
   • Windows: Credential Manager
   • Linux: Secret Service API

2. Fallback Storage: Encrypted file storage

   • Location: ~/.mcp-slack/accounts.json
   • Credentials encrypted using AES-256-CBC
   • Automatic failover if keychain unavailable
   • Permissions restricted to user only (0600)

Data Security

• Bot tokens and user tokens are encrypted at rest
• Encryption key stored separately with restricted permissions
• No plaintext credentials on disk
• Automatic cleanup of stale sessions

Performance Optimizations

• Lazy loading of workspace configurations
• Efficient caching of API responses
• Minimal startup overhead

Architecture

MCP Slack Server implements the Account Manager Tools Pattern with dual storage:

┌─────────────┐     ┌──────────────┐     ┌─────────────┐
│   Claude    │────▶│ MCP Server   │────▶│   Slack     │
│   Desktop   │     │              │     │ Workspaces  │
└─────────────┘     └──────────────┘     └─────────────┘
                            │
                    ┌───────┴───────┐
                    ▼               ▼
            ┌──────────────┐ ┌──────────────┐
            │ OS Keychain  │ │  Encrypted   │
            │   Storage    │ │ File Storage │
            └──────────────┘ └──────────────┘
                Primary         Fallback

Troubleshooting

"Secure storage unavailable"

This warning appears when keychain access is denied or unavailable. The server will continue working with temporary storage.

Missing channels or users

Ensure your bot token has the necessary OAuth scopes:

• channels:read
• chat:write
• users:read
• files:read

Performance issues

• Check network connectivity to Slack
• Verify token permissions
• Review workspace size (very large workspaces may need pagination)

Development

Building from source

git clone https://github.com/ChinchillaEnterprises/ChillMCP.git
cd ChillMCP/mcp-slacker-v3
npm install
npm run build

Contributing

Issues and pull requests are welcome at the GitHub repository.

License

MIT License - see LICENSE file for details.

Credits

Built by Chinchilla Enterprises for the MCP ecosystem.