ai-agent-slack-mcp-server

Slack MCP Server

A Model Context Protocol (MCP) server that provides Slack integration capabilities, including messaging, channel management, user management, and file uploads.

Features

• Send Messages: Send messages to Slack channels or users (with confirmation)
• Get Channels: List channels in the workspace
• Get Messages: Retrieve message history from channels
• Get Users: List users in the workspace
• Upload Files: Upload files to Slack channels (with confirmation)
• OAuth Integration: Seamless authentication via AI Agent CLI

Tools

slack_send_message

Send a message to a Slack channel or user.

Parameters:

• channel (required): Channel ID or name (e.g., "#general" or "C1234567890")
• text (required): Message text to send
• confirm (required): Must be true to confirm sending the message
• user_id (optional): User ID for authentication (defaults to "default")
• thread_ts (optional): Thread timestamp to reply to a specific message

slack_get_channels

Get a list of channels in the Slack workspace.

Parameters:

• user_id (optional): User ID for authentication (defaults to "default")
• types (optional): Channel types to include (default: "public_channel")

slack_get_messages

Get messages from a Slack channel.

Parameters:

• channel (required): Channel ID or name
• user_id (optional): User ID for authentication (defaults to "default")
• limit (optional): Number of messages to retrieve (default: 10, max: 100)
• oldest (optional): Start timestamp for message range
• latest (optional): End timestamp for message range

slack_get_users

Get a list of users in the Slack workspace.

Parameters:

• user_id (optional): User ID for authentication (defaults to "default")

slack_upload_file

Upload a file to Slack channels.

Parameters:

• channels (required): Comma-separated list of channel IDs
• file_path (required): Path to the file to upload
• confirm (required): Must be true to confirm uploading the file
• user_id (optional): User ID for authentication (defaults to "default")
• title (optional): Title of the file
• initial_comment (optional): Initial comment with the file

slack_authenticate

Check authentication status or get authentication instructions.

Parameters:

• user_id (optional): User ID to check (defaults to "default")

Installation

npm install
npm run build

Usage with AI Agent CLI

• Set up OAuth credentials (obtain from Slack App configuration):

  export SLACK_CLIENT_ID="your-slack-client-id"
  export SLACK_CLIENT_SECRET="your-slack-client-secret"
  

• Authenticate with Slack:

  ai-agent auth login slack
  

• Add to AI Agent CLI configuration (~/.agent-fleet/config.json):

  {
    "mcpServers": [{
      "name": "slack",
      "url": "node /path/to/slack-mcp-server/dist/server.js",
      "oauth": {
        "service": "slack",
        "userId": "default"
      }
    }]
  }
  

• Use with an agent:

  ai-agent chat --agent slack-assistant
  

OAuth Setup

To use this MCP server, you need to create a Slack App and configure OAuth:

• Go to api.slack.com/apps

• Create a new app

• Configure OAuth & Permissions with these scopes:

  • channels:read
  • channels:history
  • chat:write
  • files:read
  • files:write
  • users:read
  • team:read
  • groups:read
  • groups:history
  • im:read
  • im:history
  • mpim:read
  • mpim:history

• Set redirect URL to: http://localhost:3000/oauth/callback

• Copy the Client ID and Client Secret to your environment variables

Security Features

• Confirmation Required: Destructive operations (sending messages, uploading files) require explicit confirmation
• OAuth Integration: Secure token management via AI Agent CLI
• User Isolation: Support for multiple authenticated users
• Environment Variable Injection: Tokens provided securely by the AI Agent CLI

Development

# Run in development mode
npm run dev

# Build
npm run build

# Type check
npm run typecheck

# Lint
npm run lint

# Format
npm run format

Architecture

• /src/auth - OAuth2 authentication management
• /src/handlers - Slack API interaction handlers
• /src/types - TypeScript type definitions
• /src/server.ts - Main MCP server implementation

Error Handling

The server provides comprehensive error handling with helpful messages:

• Authentication errors include instructions to use ai-agent auth login slack
• Missing parameters return clear validation messages
• API errors from Slack are properly formatted and returned
• File operations validate file existence before attempting upload

Integration with AI Agent CLI

This MCP server is designed to work seamlessly with the AI Agent CLI's OAuth system:

• OAuth flow is handled by the CLI (which can open browsers)
• Tokens are injected via environment variables
• Multiple users are supported
• Automatic token refresh (when supported by Slack)
• Consistent error handling across all tools