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Coworker messaging

Send messages to users via WhatsApp and other connected channels. Use when asked to notify someone, send a message, reply to a contact, message a group, or proactively communicate through WhatsApp. Supports text, images, documents, audio, video, and stickers. Also provides group etiquette for observing group conversations — use `<no-reply/>` to stay silent when a response is not needed.

install
source · Clone the upstream repo
git clone https://github.com/Array-Ventures/coworker
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/Array-Ventures/coworker "$T" && mkdir -p ~/.claude/skills && cp -r "$T/src/mastra/skills/messaging" ~/.claude/skills/array-ventures-coworker-messaging && rm -rf "$T"
manifest: src/mastra/skills/messaging/SKILL.md
source content

Messaging

Send messages through connected channels using the 

msg
CLI.

CLI

# Send a DM
msg send --channel whatsapp --to "+1234567890" "Hello!"

# Send to a group (use the group JID)
msg send --channel whatsapp --to "120363001234@g.us" "Daily summary ready."

# Reply to a specific message
msg send --channel whatsapp --to "+1234567890" --reply-to "MSG_ID" "Got it!"

# Send an image with caption
msg send --channel whatsapp --to "+1234567890" --image /path/to/photo.jpg "Check this out"

# Send a document
msg send --channel whatsapp --to "+1234567890" --file /path/to/report.pdf

# Send a voice note
msg send --channel whatsapp --to "+1234567890" --audio /path/to/voice.ogg --ptt

# Send a video with caption
msg send --channel whatsapp --to "+1234567890" --video /path/to/clip.mp4 "Watch this"

# Send a sticker
msg send --channel whatsapp --to "+1234567890" --sticker /path/to/sticker.webp

# List connected channels and their status
msg channels

# List allowlisted WhatsApp groups
msg groups

Media Flags

FlagDescription
--image <path>
Send an image (JPEG, PNG, WebP, GIF)
--file <path>
Send a document (PDF, DOCX, etc.)
--audio <path>
Send audio (OGG, MP3, M4A)
--video <path>
Send video (MP4, MOV)
--sticker <path>
Send a sticker (WebP)
--ptt
Mark audio as voice note (push-to-talk)

When using 

--image
, 
--file
, or 
--video
, the text argument becomes the caption.

<no-reply/>
Directive

When receiving a group message that does not require a response, output 

<no-reply/>
instead of text. The bridge suppresses sending when this directive is present.

Use 

<no-reply/>
when:

  • Message is casual chatter or FYI with no actionable content
  • Conversation does not involve you and your input adds no value
  • Someone else already answered adequately

Do NOT use 

<no-reply/>
when:

  • You are @mentioned — always respond to direct mentions
  • You have genuinely useful information to contribute
  • Someone asked a question you can answer

Group Etiquette

  • Keep replies concise and relevant
  • Do not send multiple messages in quick succession to the same group
  • Wait for a natural pause before contributing to ongoing threads
  • Never send sensitive information (passwords, keys, personal data) to groups

Channels

Channel
--channel
--to
format
WhatsApp
whatsapp
+{number}
(DM) or 
{jid}@g.us
(group)