Agent skill · writing content · anthropics
slack-messaging
Guidance for composing well-formatted, effective Slack messages using mrkdwn syntax
Why this skill is useful
Codifies best practices for effective Slack messaging that the AI could infer but now doesn't have to guess.
What it needs
About 2k tokens when loaded. Last updated 2026-08-07. 23,345 stars on the source repository.
What this skill does
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 slacksendmessage, slacksendmessagedraft, or slackcreatecanvas. 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 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 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. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills anthropics/slack-messaging