slack-messaging

Q: How do I install slack-messaging?

Run npx skills add https://github.com/anthropics/knowledge-work-plugins --skill slack-messaging in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/slack-messaging/ (personal) or .claude/skills/slack-messaging/ (project).

by anthropics OfficialProductivity & Automation

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

Installs: 4K
Last 24h: —
Trending rank: —
Security: Warn

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/anthropics/knowledge-work-plugins --skill slack-messaging

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads slack-messaging automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

Security audits

Independent scans of the skill's instructions and bundled files.

Gen Agent Trust Hub PassSAFE ·This skill provides helpful guidance and formatting rules for composing Slack messages. No security issues were detected.

Socket PassNo alerts

Snyk PassLOW ·Risk: LOW · No issues

Runlayer WarnMEDIUM ·1/1 file flagged

ZeroLeaks PassNONE ·Score: 93/100 · 2 sections analyzed

SKILL.md

The instructions your agent reads when the skill is triggered.

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.

FAQ

What does the slack-messaging skill do?

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

How do I install slack-messaging?

Run npx skills add https://github.com/anthropics/knowledge-work-plugins --skill slack-messaging in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/slack-messaging/ (personal) or .claude/skills/slack-messaging/ (project).

Which AI agents can use slack-messaging?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is slack-messaging safe to install?

Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk passed; Runlayer flagged items to review; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.

Who maintains slack-messaging?

It is published by anthropics in anthropics/knowledge-work-plugins, and it is an official skill from the maker of the technology it covers. It has 3,959 recorded installs.