Slack Messaging

1---2name: slack-messaging3description: Guidance for composing well-formatted, effective Slack messages using mrkdwn syntax4---5 6# Slack Messaging Best Practices7 8This skill provides guidance for composing well-formatted, effective Slack messages.9 10## When to Use11 12Apply 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`.13 14## Slack Formatting (mrkdwn)15 16Slack uses its own markup syntax called **mrkdwn**, which differs from standard Markdown. Always use mrkdwn when composing Slack messages:17 18| Format | Syntax | Notes |19|--------|--------|-------|20| Bold | `*text*` | Single asterisks, NOT double |21| Italic | `_text_` | Underscores |22| Strikethrough | `~text~` | Tildes |23| Code (inline) | `` `code` `` | Backticks |24| Code block | `` ```code``` `` | Triple backticks |25| Quote | `> text` | Angle bracket |26| Link | `<url\|display text>` | Pipe-separated in angle brackets |27| User mention | `<@U123456>` | User ID in angle brackets |28| Channel mention | `<#C123456>` | Channel ID in angle brackets |29| Bulleted list | `- item` or `• item` | Dash or bullet character |30| Numbered list | `1. item` | Number followed by period |31 32### Common Mistakes to Avoid33 34- Do NOT use `**bold**` (double asterisks) — Slack uses `*bold*` (single asterisks)35- Do NOT use `## headers` — Slack does not support Markdown headers. Use `*bold text*` on its own line instead.36- Do NOT use `[text](url)` for links — Slack uses `<url|text>` format37- Do NOT use `---` for horizontal rules — Slack does not render these38 39## Message Structure Guidelines40 41- **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.42- **Keep it short.** Aim for 1-3 short paragraphs. If the message is long, consider using a Canvas instead.43- **Use line breaks generously.** Walls of text are hard to read. Separate distinct thoughts with blank lines.44- **Use bullet points for lists.** Anything with 3+ items should be a list, not a run-on sentence.45- **Bold key information.** Use `*bold*` for names, dates, deadlines, and action items so they stand out when scanning.46 47## Thread vs. Channel Etiquette48 49- **Reply in threads** when responding to a specific message to keep the main channel clean.50- **Use `reply_broadcast`** (also post to channel) only when the reply contains information everyone needs to see.51- **Post in the channel** (not a thread) when starting a new topic, making an announcement, or asking a question to the whole group.52- **Don't start a new thread** to continue an existing conversation — find and reply to the original message.53 54## Tone and Audience55 56- Match the tone to the channel — `#general` is usually more formal than `#random`.57- 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).58- When writing announcements, use a clear structure: context, key info, call to action.