Post to Slack from Claude Cowork

Claude Cowork can send and schedule Slack channel messages through Postiz. Add the Postiz connector to Cowork once, then name the channel and describe the update, and Cowork posts it through the Postiz Slack app from the Claude desktop app. It can pull the message text from a local document and schedule it for later, with no terminal involved.

Setup Guide

Please make sure there is always a human in the loop.

How to send to Slack from Claude Cowork

Add Postiz to Claude Cowork once as a connector, then ask for Slack messages in plain language. Cowork calls Postiz for you and confirms what it scheduled.

Setup, then just ask

# One-time setup in Claude Cowork (no terminal)
# Cowork tab > Customize > Connectors > + Add custom connector
#   Name: Postiz
#   URL:  https://mcp.postiz.com/mcp-oauth-dynamic
# Sign in to Postiz and approve access

# Then just ask Claude Cowork:
> Post the weekly update to #general
  on Slack tomorrow at 9am

Claude Cowork: Done! Your Slack post is scheduled.

What can Claude Cowork do on Slack?

Claude Cowork can use every Slack option that Postiz exposes. Describe the result you want and Cowork picks the matching settings.

📢

Channel Messaging

Post messages to any Slack channel your bot has access to. Share updates, announcements, and notifications automatically.

⏰

Scheduled Messages

Schedule messages for the perfect time. Queue up announcements, reminders, and updates to post when your team is most active.

🖼

Media Sharing

Attach images, files, and rich media to your Slack messages. Share screenshots, reports, and visual updates with your team.

👥

Team Communications

Automate recurring team updates, standup summaries, and status reports across multiple channels simultaneously.

🤖

Bot Integration

Leverage Slack bot tokens for seamless posting. Your AI agent authenticates once and posts on behalf of your workspace.

📅

Multi-Channel Posting

Target different channels for different content types. Send engineering updates to #dev and marketing wins to #general.

How does Claude Cowork send to Slack?

You describe what you want in plain language and Claude Cowork handles the Postiz calls for you. Here is how a typical conversation goes.

Find Your Slack Integration

Ask Claude Cowork whether your Slack account is connected. It also checks which options the platform supports.

Example conversation

> Is my Slack account connected to Postiz?

Claude Cowork: Yes — your Slack account is connected
  and ready. Want me to post something?

Choose Your Channel

Identify the Slack channel ID where you want to post. You can find channel IDs in Slack by right-clicking a channel and selecting 'View channel details'.

Example conversation

> Draft a Slack post about our new
  feature launch

Claude Cowork: Here's a draft for Slack:
  "We just shipped something big..."
  Want me to add media and schedule it?

Create Your Post

Send a message to your Slack channel with the channel ID in settings. Schedule it for later or post immediately.

Example conversation

> Yes — add screenshot.png and schedule
  it for tomorrow at 9am

Claude Cowork: Done! Scheduled on Slack for
  tomorrow at 9:00 AM.

Which Slack settings can Claude Cowork apply?

Mention any of these in plain language and Claude Cowork sets them for you. These are the Slack options it can apply to any post.

Field	Type	Required	Description
`__type`	string	Yes	Must be "slack"
`channel`	string	Yes	Slack channel ID (e.g. C12345)

Common Configurations

Ask Claude Cowork for any of these common Slack scenarios and it applies the matching settings.

General Channel Announcement

Just ask

> Post it with: General Channel Announcement

Claude Cowork: Got it. Applying:
  channel: C12345

Engineering Updates

Just ask

> Post it with: Engineering Updates

Claude Cowork: Got it. Applying:
  channel: C67890

Marketing Channel Post

Just ask

> Post it with: Marketing Channel Post

Claude Cowork: Got it. Applying:
  channel: CABCDE

What is Claude Cowork?

Claude Cowork is Anthropic's agentic assistant for knowledge workers. It runs in the Claude desktop app on macOS and Windows (and on the web) on paid Claude plans, uses the same agentic architecture as Claude Code without a terminal, and can read local files, use connectors, and run multi-step tasks such as sending to Slack through Postiz. It is not the same as Claude Code (the terminal agent) or the Postiz connector in Claude.ai; read the full comparison on the Claude Cowork hub.

💻

Desktop Native

Claude Cowork runs directly on your desktop, connecting to your local files and apps. No dashboard tabs or terminal needed to manage your social media workflow.

🔗

App Integrations

Connects to Google Drive, Gmail, DocuSign, and more. Pull content from your existing tools and publish it to social media seamlessly.

🤖

Autonomous Tasks

Schedule recurring tasks with cron jobs. Claude Cowork can post your Slack messages on a schedule without you having to ask each time.

How Postiz Works with Claude Cowork

Postiz is an MCP server, and Claude Cowork supports custom connectors over remote MCP. Add the Postiz link once in Customize, then Connectors, sign in with OAuth, and Cowork sees the Postiz tools for listing channels, uploading media, scheduling Slack messages, and reading analytics. No API key or terminal is needed.

✓Open the Cowork tab, then Customize, then Connectors, and add a custom connector named Postiz
✓Paste the Postiz MCP link and sign in to Postiz when prompted (OAuth, no API key)
✓Cowork discovers the Postiz tools automatically, including your connected Slack channel
✓Ask in plain language; Cowork chains upload, settings, and scheduling steps for you
✓Prefer the Postiz skill and CLI? Install the postiz-agent plugin instead and authenticate with postiz auth:login

Connect Postiz to Claude Cowork

# Option 1: custom connector (recommended, full toolset)
Cowork > Customize > Connectors > +
  Name: Postiz
  URL:  https://mcp.postiz.com/mcp-oauth-dynamic
  Sign in to Postiz and approve

# Option 2: official connector (posting + scheduling)
claude.ai/directory/postiz > Connect

# Option 3: Postiz skill + CLI (terminal)
npm install -g postiz
postiz auth:login

How do Slack workflows run in Claude Cowork?

Two ways: ask Cowork directly in the desktop app, where it can read the content from your local files, or set up a scheduled task that runs in the cloud on a timetable you choose.

From your desktop files

Local folders, Google Drive, no terminal

Point Claude Cowork at a document or media file on your computer and tell it where and when to send. It reads the file, uploads media through Postiz, applies the Slack settings, and schedules the result for your Slack workspace.

Claude Cowork

You: Post the update in ~/Docs/update.md
  to #general on Slack tomorrow at 9am

Claude Cowork: Reading update.md...
  1. Drafted the message (Slack formatting)
  2. Resolved #general channel ID
  3. Scheduled for 9:00 AM

  Done! Want a Discord copy too?

Scheduled tasks

Recurring Slack messages without a cron server

Type /schedule in any Cowork task to make it recurring. Scheduled tasks run in the cloud with the connectors you have set up, so your computer does not need to be awake for Cowork to send to Slack on time.

Claude Cowork scheduled task

/schedule

"Every Friday at 4pm, summarize this week's notes in ~/Docs/week.md and post the summary to #general on Slack."

Claude Cowork will, on each run:
  1. Read the source file or folder
  2. Draft the Slack content
  3. Schedule it through Postiz
  4. Report back what it did

Why Claude Cowork + Postiz for Slack

Cowork brings the desktop context and the scheduling; Postiz brings the Slack publishing, media handling, and analytics. Together they replace a scheduler dashboard with a conversation.

✓No terminal: Postiz is a connector in the Claude app, added once
✓Reads Slack messages content from local folders and connected apps like Google Drive
✓Scheduled tasks run in the cloud on a timetable you set
✓Cross-posts Slack content to other Postiz channels in one request
✓Uses the same Postiz account, channels, and calendar as your dashboard and other agents

Postiz tools Cowork can call

# Discovery
integrationList        # your connected channels
integrationSchema      # Slack settings and limits
triggerTool            # live data (boards, flairs, lists)

# Publishing
uploadFromUrlTool      # media upload
integrationSchedulePostTool
postsListTool          # what is scheduled
postSettingsTool

# Custom MCP link only
generateImageTool, generateVideoTool, clippingTool

Also Works with OpenClaw

Postiz works with any AI agent that can run commands or call MCP tools — you ask, the agent does the work. That includes OpenClaw, the open-source personal AI agent, which reads the Postiz skill and runs the CLI rather than connecting over MCP.

🦀

OpenClaw

Open-source AI agent

OpenClaw reads the Postiz skill so it knows what it can do, then autonomously discovers your Slack integration, identifies the correct channel, and sends your message.

OpenClaw

> Post a deployment update to #engineering
  on Slack

OpenClaw: Done! Scheduled on Slack for
  tomorrow at 9:00 AM.

Slack + Other Platforms

Post the same announcement to Slack and other platforms in a single request. Each platform gets its own settings.

Example

> Post "Excited to announce our new feature!" to
  Slack and LinkedIn tomorrow at 9am, then schedule
  a daily tip on Slack every weekday at 10am

Claude Cowork: Done! Scheduled:
  - Slack + LinkedIn: tomorrow 9:00 AM
  - Daily tips on Slack: Mon-Fri 10:00 AM

What can you ask Claude Cowork to send on Slack?

Anything you would type into the Postiz dashboard, phrased as a request. These are prompts people actually use for Slack.

You say to Claude Cowork	What Postiz does
`Post the weekly update in ~/Docs/update.md to #general on Slack tomorrow at 9am`	Reads the file, resolves the channel ID, and schedules the message
`Share launch.png in #marketing with a note that the campaign is live`	Uploads the image through Postiz and sends it to the channel
`Move Friday's Slack announcement to Monday at 10am`	Finds the scheduled post and changes its publish time

What should you know before posting to Slack from Claude Cowork?

Cowork handles these rules for you, but knowing them explains why it sometimes asks a follow-up question before scheduling.

✓channel is required and takes the Slack channel ID (like C12345), not the #name. Cowork resolves it for you.
✓The Postiz Slack app must be able to post in the channel; invite it to private channels first.
✓Slack renders its own markdown flavor (mrkdwn). Ask Cowork for Slack formatting if you rely on bold or lists.
✓Files are uploaded through Postiz before sending; Cowork handles that when you name the file.

Claude Cowork and Slack: frequently asked questions

How do I post to Slack from Claude Cowork?

Add Postiz as a custom connector in Cowork (Customize, then Connectors, URL https://mcp.postiz.com/mcp-oauth-dynamic), sign in to Postiz, and ask Cowork to post to a channel. It resolves the channel ID from your Postiz Slack channel, formats the message, and schedules it. No terminal or Slack app credentials are needed.

Can Claude Cowork post to a private Slack channel?

Yes, as long as the Postiz Slack app has been invited to that channel. Once it is a member, Cowork can schedule messages there like any public channel. If a post fails, invite the app to the channel in Slack and ask Cowork to retry.

Can Cowork schedule Slack messages for later?

Yes. Every Postiz post has a publish time, so ask Cowork to send the update at 9am tomorrow or next Monday and it schedules accordingly. You can also ask what is scheduled, move a message, or cancel it, all from the same Cowork conversation.

Is this different from Slack posting with Claude Code?

The Postiz features are the same. Claude Code is Anthropic's terminal agent and connects with a claude mcp add command or the Postiz CLI. Claude Cowork is the desktop agent, so Postiz is added as a connector and Cowork can read the update straight from a document on your computer.

Does Cowork need a Slack bot token?

No. Postiz connects to your workspace with its own Slack app when you add Slack in the Postiz dashboard, and Cowork authenticates to Postiz through OAuth. You never paste tokens, and removing the Postiz app from Slack revokes access immediately.

Related guides

More Claude Cowork platform guides

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