message/sendEphemeral

When to Use

• Private validation feedback: Notify a user that their form submission had validation errors (e.g., missing required fields) without broadcasting the failure to the entire channel.
• Contextual help hints: Show targeted help text to a specific user after they invoke a slash command — guidance visible only to them, in the channel where they typed the command.
• Moderation notices: Warn a user privately that a message they posted violated channel guidelines, without calling them out publicly in front of other members.
• Onboarding prompts: Guide new channel members with orientation tips (pin location, channel purpose, conventions) shown only to them when they first join.
• Debug and diagnostic output: Show pipeline diagnostic information or verbose error details to an administrator in a channel without polluting the conversation for everyone else.

Configuration

Connection

Operation

Sample Configuration

{
  "resource": "message",
  "operation": "sendEphemeral",
  "botToken": "{{ $credentials.slackBotToken }}",
  "channel": "C04GENERALCH",
  "targetUserId": "{{ $input.userId }}",
  "text": ":warning: Your expense report submission was incomplete. Missing fields: *{{ $input.missingFields }}*.\nPlease resubmit at <https://expenses.internal/submit|expenses.internal>."
}

Validation Errors

Output

Success Port

Fires when Slack confirms the ephemeral message was delivered. Note that ephemeral messages do not have a persistent messageTs — they cannot be updated, deleted, or replied to.

Error Port

Fires when the channel or user cannot be found, the bot lacks channel membership, or the API call fails.

Sample Output

{
  "status": "ok",
  "errorCode": "",
  "payload": {
    "ok": true,
    "message_type": "ephemeral"
  }
}

Expression Reference

Node Policies & GuardRails

Examples

Form Validation Error Feedback

{
  "resource": "message",
  "operation": "sendEphemeral",
  "botToken": "{{ $credentials.slackBotToken }}",
  "channel": "C04HRFORMSVC",
  "targetUserId": "{{ $input.submitterUserId }}",
  "text": ":x: Your time-off request could not be processed.\n\n*Validation errors:*\n• Start date must be a future date\n• Reason field is required\n\nPlease <https://forms.internal/time-off|resubmit the form> with the corrections."
}

After a form validation node detects errors in a time-off request, this ephemeral message is shown only to the submitter in the HR forms channel. No other HR team members see the error, preserving the submitter's privacy.

Admin Diagnostics in Shared Channel

{
  "resource": "message",
  "operation": "sendEphemeral",
  "botToken": "{{ $credentials.slackBotToken }}",
  "channel": "C04DEPLOYCHAN",
  "targetUserId": "{{ $input.triggerUserId }}",
  "text": ":mag: *Deploy Diagnostics (visible to you only)*\nBuild ID: `{{ $input.buildId }}`\nArtifact hash: `{{ $input.artifactHash }}`\nDeploy target: `{{ $input.targetEnv }}`\nLogs: <{{ $input.logUrl }}|View full logs>"
}

A deployment workflow posts verbose diagnostic details (build IDs, artifact hashes, log URLs) only to the engineer who triggered the deploy, in the shared #deploys channel. Other channel members see only the standard deploy notification posted via message/send.

Onboarding Welcome Tip

{
  "resource": "message",
  "operation": "sendEphemeral",
  "botToken": "{{ $credentials.slackBotToken }}",
  "channel": "C04GENERAL01",
  "targetUserId": "{{ $input.newMemberUserId }}",
  "text": ":wave: Welcome to *#general*, {{ $input.displayName }}!\n\n*Quick tips:*\n• Keep posts relevant to company-wide announcements\n• Use <#C04WATERCOOL|#water-cooler> for casual chat\n• Reach the admin team at <@U04ADMINTEAM>\n\nThis message is only visible to you."
}

An onboarding workflow triggers when a new member joins #general and shows them a contextual welcome tip. Because it is ephemeral, the channel is not cluttered with a welcome for each new member, and other members are not interrupted.