| name | slack-messaging |
| description | Guidance for composing well-formatted, effective Slack messages using mrkdwn syntax |
Slack Messaging Best Practices
This skill provides guidance for composing well-formatted, effective Slack messages.
When to Use
Apply this skill whenever composing, drafting, or helping the user write a Slack message — including when using slack_send_message, slack_send_message_draft, or slack_create_canvas.
Slack Formatting (mrkdwn)
Slack uses its own markup syntax called mrkdwn, which differs from standard Markdown. Always use mrkdwn when composing Slack messages:
| Format | Syntax | Notes |
|---|
| Bold | *text* | Single asterisks, NOT double |
| Italic | _text_ | Underscores |
| Strikethrough | ~text~ | Tildes |
| Code (inline) | `code` | Backticks |
| Code block | ```code``` | Triple backticks |
| Quote | > text | Angle bracket |
| Link | <url|display text> | Pipe-separated in angle brackets |
| User mention | <@U123456> | User ID in angle brackets |
| Channel mention | <#C123456> | Channel ID in angle brackets |
| Bulleted list | - item or • item | Dash or bullet character |
| Numbered list | 1. item | Number followed by period |
Common Mistakes to Avoid
- Do NOT use
**bold** (double asterisks) — Slack uses *bold* (single asterisks)
- Do NOT use
## headers — Slack does not support Markdown headers. Use *bold text* on its own line instead.
- Do NOT use
[text](url) for links — Slack uses <url|text> format
- Do NOT use
--- for horizontal rules — Slack does not render these
Message Structure Guidelines
- Lead with the point. Put the most important information in the first line. Many people read Slack on mobile or in notifications where only the first line shows.
- Keep it short. Aim for 1-3 short paragraphs. If the message is long, consider using a Canvas instead.
- Use line breaks generously. Walls of text are hard to read. Separate distinct thoughts with blank lines.
- Use bullet points for lists. Anything with 3+ items should be a list, not a run-on sentence.
- Bold key information. Use
*bold* for names, dates, deadlines, and action items so they stand out when scanning.
Thread vs. Channel Etiquette
- Reply in threads when responding to a specific message to keep the main channel clean.
- Use
reply_broadcast (also post to channel) only when the reply contains information everyone needs to see.
- Post in the channel (not a thread) when starting a new topic, making an announcement, or asking a question to the whole group.
- Don't start a new thread to continue an existing conversation — find and reply to the original message.
Tone and Audience
- Match the tone to the channel —
#general is usually more formal than #random.
- Use emoji reactions instead of reply messages for simple acknowledgments (though note: the MCP tools can't add reactions, so suggest the user do this manually if appropriate).
- When writing announcements, use a clear structure: context, key info, call to action.
