Slack Message Formatting
Write Slack messages that render: mrkdwn vs markdown by posting route, Block Kit and a lint script
Free
Works with the AI Agents you already use
Claude Code
Cursor
Codex CLI
Muse
Dots+22 moreClaude CodeCursorCodex CLIMuseDots
OpenClaw
Manus
Grok
Grok Bot+18 agentsSlack Message Formatting
Example session with this skill installed
Post this to #release through the Slack Web API (chat.postMessage):
Deploy done for v2.3
Changes
- Faster search
- Fixed login bug
@here please check
- Read your context and instructions
- Compiled the slack message formatting
Summary
The draft uses CommonMark, which chat.postMessage does not render. I checked it with the lint script and rewrote it in native mrkdwn.
Lint result (scripts/lint_slack_text.py)
4 issue(s) to fix:
L1 [bold-commonmark] '**Deploy done**'
-> CommonMark bold `**x**` -> native mrkdwn uses `*x*`
L1 [md-link] '[v2.3](https://example.com/r/23)'
-> markdown link `[t](url)` -> native uses `<url|t>`
L3 [heading] '## C'
-> `#` headings do not work -> use `*Heading*` (bold) or a Block Kit header
L7 [bare-at-mention] '@here'
-> plain @here/@channel does not notify -> use `<!here>` `<!channel>`
Message to send (text field)
*Deploy done* for <https://example.com/r/23|v2.3>
*Changes*
• Faster search
• Fixed login bug
<!here> please check
Next steps
- The list has only two items, so plain bullets are fine. For three or more items or nested lists, build rich_text blocks with scripts/rich_text_blocks.py and keep this text as the notification fallback.
- Confirm you want to notify the whole channel with <!here> before sending.
Connects securely to your tools. The creator never sees your data.
About this skill
Makes your agent write Slack messages that render correctly.
Slack does not use standard markdown. It uses mrkdwn, and the bold syntax depends on how you post: *bold* through the Web API or a webhook, **bold** through connectors that convert CommonMark. Agents often get this wrong, so bold turns into italics, links show as raw brackets and lists collapse into one line. This skill makes the agent pick the posting route first, then write in that route's syntax.
What it covers
- Bold, italic, links and lists for each posting route (Web API, incoming webhook, Slack MCP servers, the Slack connector in Claude)
- Real nested lists with Block Kit rich_text, plus a converter script
- Mentions, channel links and dates by ID, and escaping
- Block Kit for headings, tables and buttons
- Keeping messages short: who does what to whom, 10 lines or less, no file paths or internal names
- A checklist to run before sending
Scripts (Python 3.9+, no dependencies, no network)
- scripts/lint_slack_text.py finds markdown that will not render in Slack. --fix prints a converted version.
- scripts/rich_text_blocks.py turns an indented list into Block Kit rich_text JSON, with --text for the plain fallback.
The scripts never call Slack. Sending is up to you or your agent.
Free and MIT licensed. Source: https://github.com/kojikojikojikoji/slack-message-formatting
How to use
Skills on Agensi run inside your AI agent. Copy the prompt, paste it into your agent, and it connects to Agensi and installs this skill for you. If a payment is needed, your agent shows it to you first.
Reviews
No reviews yet
Be one of the first to try it. Every listed skill passes our trust checks below.
Security scanned
Passed our 8-point scan before listing
Fresh listing
Recently published to Agensi
Free forever
No account required to browse
Trust & safety
Security scanned
Verified clean 1 day ago
- Free to download with an account
Requires
Slack
Python
Git