Mcp Slack

mcp-slack

MCP server for Slack integration, built with FastMCP. Provides tools for listing channels, reading messages, and posting to Slack.

Install

pip install -e ".[dev]"

Environment Variables

| Variable | Required | Description | |----------|----------|-------------| | SLACK_BOT_TOKEN | Yes | Bot User OAuth Token (xoxb-...) | | SLACK_DEFAULT_CHANNEL | No | Fallback channel for slack_post_message |

Copy .env.example to .env and fill in your values.

Tools

| Tool | Description | |------|-------------| | slack_list_channels | List all channels accessible by the bot | | slack_read_channel(channel, limit?) | Read last N messages from a channel (default: 20, max: 100) | | slack_post_message(channel, text) | Send a message to a channel |

The channel parameter accepts either a channel name (without #) or a Slack channel ID.

Slack App Setup

1. Go to api.slack.com/apps and create a new app
2. Under OAuth & Permissions, add the required Bot Token Scopes for the tools you want to use:

| Tool | Required Bot Scopes | |------|---------------------| | slack_list_channels | channels:read, groups:read | | slack_read_channel | channels:history, groups:history | | slack_post_message | chat:write |

Note: Private-channel access (groups:*) and DM scopes are only needed if the bot operates outside public channels.

1. Install the app to your workspace
2. Copy the Bot User OAuth Token (xoxb-...) to SLACK_BOT_TOKEN
3. Invite the bot to channels it should access: /invite @your-bot-name

Troubleshooting: missing_scope Error

If a tool fails with a missing_scope error, it means the bot doesn't have the necessary permissions to perform that action. Check the error message to see which scope is missing, cross-reference it with the table above, and add the missing scope in your Slack App's OAuth & Permissions page. (Remember to reinstall the app to your workspace after changing scopes!)

Usage

Standalone

mcp-slack

Claude Desktop config

{
  "mcpServers": {
    "slack": {
      "command": "mcp-slack",
      "env": {
        "SLACK_BOT_TOKEN": "xoxb-your-token"
      }
    }
  }
}

Development

pip install -e ".[dev]"
ruff check src/ tests/
ruff format src/ tests/
pytest

License

MIT

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: antonio-mello-ai
• Source: antonio-mello-ai/mcp-slack
• License: MIT

Install and usage instructions live in the source repository linked above.