Knowledge-work-plugins slack-messaging

Guidance for composing well-formatted, effective Slack messages using mrkdwn syntax

install

source · Clone the upstream repo

git clone https://github.com/anthropics/knowledge-work-plugins

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/anthropics/knowledge-work-plugins "$T" && mkdir -p ~/.claude/skills && cp -r "$T/partner-built/slack/skills/slack-messaging" ~/.claude/skills/anthropics-knowledge-work-plugins-slack-messaging && rm -rf "$T"

manifest: partner-built/slack/skills/slack-messaging/SKILL.md

source content

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.