| name | slack-notify |
| description | Send Slack notifications via Incoming Webhook with mrkdwn formatting. Use this skill whenever: (1) you need to send a message or notification to Slack, (2) alerting users about task completion or results, (3) sharing summaries, reports, or status updates to a Slack channel, (4) another skill or workflow needs to notify someone via Slack. Even if the user doesn't say 'Slack' explicitly, use this skill when they mention sending notifications, alerting a channel, or posting updates. |
Slack Notify
Send messages to Slack channels via Incoming Webhook with mrkdwn formatting support.
Prerequisites
A Slack Incoming Webhook URL is required. Provide it via either:
- Environment variable (recommended for repeated use):
export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/T.../B.../xxx"
--webhook-url argument (for one-off or per-channel sends):
uv run scripts/send_slack.py --webhook-url "https://hooks.slack.com/services/..." --text "hello"
The --webhook-url argument takes priority over the environment variable when both are present.
Usage
Send a simple message:
uv run scripts/send_slack.py --text "Deployment complete :rocket:"
Send with mrkdwn formatting:
uv run scripts/send_slack.py --text "*Build succeeded*\nBranch: \`main\`\nCommit: <https://github.com/org/repo/commit/abc123|abc123>"
Send a multiline message via stdin (useful for longer content):
cat <<'EOF' | uv run scripts/send_slack.py
*Daily Report* :bar_chart:
> Total requests: 12,345
> Error rate: 0.02%
> P99 latency: 120ms
_Generated at 2025-03-22 09:00 UTC_
EOF
Send to a specific webhook (overrides env var):
uv run scripts/send_slack.py --webhook-url "https://hooks.slack.com/services/T.../B.../xxx" --text "Alert!"
Arguments
| Argument | Description |
|---|
--text, -t | Message text in mrkdwn format |
--webhook-url | Incoming Webhook URL (overrides SLACK_WEBHOOK_URL) |
| (stdin) | If --text is not provided, reads message from stdin |
mrkdwn Quick Reference
Slack uses its own markup syntax called mrkdwn (not standard Markdown). Key differences from Markdown:
| Syntax | Renders as |
|---|
*bold* | bold |
_italic_ | italic |
~strikethrough~ | strikethrough |
`inline code` | inline code |
```code block``` | code block |
> quote | blockquote |
\n | newline (in --text arg) |
<URL|display text> | hyperlink |
<@U012ABC> | mention user |
<!channel> | @channel |
<!here> | @here |
:emoji_name: | emoji |
Important rules:
- Slack mrkdwn is NOT standard Markdown.
**bold** will not work — use *bold* instead.
- Formatting markers (
*, _, ~, `) MUST have a whitespace or newline before the opening marker. They will NOT render after punctuation (especially CJK punctuation like ：, ，, 。). For example:
狀態： *running* — works (space before *)狀態：*running* — broken (no space before *)*running* at line start — works
Workflow
When using this skill to send notifications:
- Compose the message content using mrkdwn syntax
- Choose the delivery method:
--text for single-line or short messages- stdin pipe for multiline or template-based messages
- Run the script via
uv run
- Verify the output is
ok
Exit Codes
| Code | Meaning |
|---|
| 0 | Message sent successfully |
| 1 | Error (missing webhook URL, missing message, or Slack API error) |
Troubleshooting
| Error | Solution |
|---|
| "no webhook URL provided" | Set SLACK_WEBHOOK_URL env var or pass --webhook-url |
| "no message provided" | Pass --text or pipe content via stdin |
| Slack returned non-200 | Check webhook URL is valid and not revoked |
| "channel_not_found" | The webhook's associated channel was deleted |
| "invalid_payload" | Check message formatting — mrkdwn syntax may be malformed |
