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Slack Messaging

AnthropicOfficialCreated by SalesforceDistributed by Anthropic

  • Skill
  • Guidelines
  • Automation and integrations
  • MIT
  • No issues found
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From the author

Guidance for composing well-formatted, effective Slack messages using mrkdwn syntax
— the description by Salesforce

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a comprehensive guide for drafting professional and readable messages within Slack. It covers the specific mrkdwn syntax required for formatting text, such as bolding, linking, and creating lists, while also offering best practices for message structure, tone, and channel etiquette to ensure clear communication.

What it does

  • Explains the mrkdwn syntax for text formatting including bold, italics, and code blocks
  • Provides instructions for correctly linking URLs and mentioning users or channels
  • Offers structural advice for writing concise and scannable messages
  • Outlines etiquette for using threads versus channel-wide posts
  • Suggests strategies for matching tone to specific channel contexts
  • Identifies common formatting mistakes to avoid when drafting messages

When to use it

  • When drafting a message to be sent via an automated Slack integration
  • When preparing content for a Slack Canvas
  • When you need to ensure a message is formatted correctly for readability
  • When you want to improve the clarity and impact of team communications

Advantages

  • Ensures messages are formatted correctly for the Slack interface
  • Helps improve readability through structured text and bullet points
  • Reduces clutter by promoting proper thread and channel usage
  • Standardizes the approach to professional communication in Slack

Usage examples

“How do I bold text in a Slack message?”
The agent explains that Slack uses single asterisks around text, such as *bold*, rather than standard markdown double asterisks.
“Draft a message for the team about the upcoming project deadline.”
The agent writes a concise message using mrkdwn, leading with the deadline, using bullet points for tasks, and bolding key dates.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/anthropics/slack-messaging/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip slack-messaging.zip -d .agents/skills

Documentation by Salesforce

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:

FormatSyntaxNotes
Bold*text*Single asterisks, NOT double
Italic_text_Underscores
Strikethrough~text~Tildes
Code (inline)`code`Backticks
Code block```code```Triple backticks
Quote> textAngle 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 • itemDash or bullet character
Numbered list1. itemNumber 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.

Files

LICENSE

The MIT License (MIT)

Copyright (c) 2020- Slack Technologies, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Requirements and compatibility

Written for: Claude Code, Claude apps

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by
Salesforce
Publisher
Anthropic (Official)
Distributed by
Anthropic
Source
anthropics/knowledge-work-plugins · partner-built/slack/skills/slack-messaging · commit e050c2e
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from partner-built/slack/LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced

AutoGineer is not affiliated with or endorsed by Salesforce or Anthropic.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download slack-messaging.zip