Send Your First Message to Slack via AI Agent

Your sandbox is running. Your agent is alive inside it. Now — can it actually do anything?

Let's find out by sending a real message to Slack.

Why Slack?

Slack is the perfect first test. It's: - External (proves your agent can reach outside itself) - Verifiable (you can see the message land in real time) - Useful (this is the foundation of real automation workflows)

If your agent can send a Slack message, it can do a lot more.

What You Need Before Starting

• A running NemoClaw sandbox (see Blog 1)
• A Slack workspace you control
• A Slack Bot Token (xoxb-...) with chat:write permission
• The channel ID you want to post to

Step 1: Get Your Slack Bot Token

Go to api.slack.com/apps and create a new app.

Under OAuth & Permissions, add the scope:

chat:write

Install the app to your workspace. Copy the Bot User OAuth Token — it starts with xoxb-.

Step 2: Find Your Channel ID

In Slack, right-click the channel name → Copy link. The channel ID is the last segment:

https://app.slack.com/client/T0123ABCD/C0456EFGH
                                        ^^^^^^^^^^
                                        This is your channel ID

Step 3: Configure the MCP Slack Plugin

Inside your sandbox, check what plugins are available:

openclaw plugins list

Look for a Slack or MCP messaging plugin. If it's there but disabled, the config lives on your host, not inside the sandbox.

On your host machine, open or create:

~/.config/openclaw/config.json

Add your Slack credentials:

{
  "plugins": {
    "slack": {
      "enabled": true,
      "token": "xoxb-your-token-here",
      "defaultChannel": "C0456EFGH"
    }
  }
}

Restart your sandbox after saving:

# Exit sandbox first
exit

# Restart
nemoclaw restart kaav-assistant
nemoclaw shell kaav-assistant

Step 4: Send the Message

From inside your sandbox, ask your agent to send a message:

Send a message to Slack: "Hello from NemoClaw — agent is live."

Or if you're testing via the MCP interface directly:

/mcp slack send --channel C0456EFGH --text "Hello from NemoClaw"

Step 5: Verify It Landed

Switch to Slack. You should see the message in your target channel, posted by your bot.

If you see it — congratulations. You just closed the loop between an isolated AI sandbox and the real world.

What Actually Happened Under the Hood

This is worth understanding because it shapes how you build more complex workflows.

You (in sandbox)
    └──► Agent processes your request
             └──► MCP Slack plugin called
                      └──► Plugin sends HTTP request to Slack API
                                └──► Message appears in Slack

Your agent never directly hit the Slack API. It went through the MCP (Model Context Protocol) plugin layer — a controlled interface that handles external calls on the agent's behalf.

This is important: the sandbox doesn't have open internet access. The MCP plugin is a curated, permission-gated channel for specific external services. Slack works because there's an approved plugin for it. Random HTTP calls to arbitrary URLs? Still blocked.

Troubleshooting

Message didn't send — channel_not_found Make sure your bot has been invited to the channel:

/invite @your-bot-name

missing_scope error Your token doesn't have chat:write. Go back to your Slack app settings and add it, then reinstall.

Plugin not found in openclaw plugins list The plugin may need to be installed on the host gateway. See Blog 3 for how ACP agents and host-side config work.

What You've Proved

By sending that one Slack message, you've demonstrated:

• Your sandbox is running and your agent is responsive
• The MCP plugin layer is wired up correctly
• External communication from an isolated agent is possible — through controlled channels
• You have the foundation for real automation: Slack alerts, status updates, notifications, auto-responses

From here, the patterns scale. Monitor a process and Slack on failure. Summarise a doc and post it. Watch a channel and respond to mentions.

It all starts with that first message.