slack-messaging

name	slack-messaging
description	Send proactive messages to Slack users and channels using slack_cli
allowed-tools	Bash(slack_cli:*)

Slack Messaging Skill

Send messages to Slack users and channels for TPM follow-ups, notifications, and reports.

Quick Reference

# Send DM to user
slack_cli send-dm --user-id U12345ABC --message "Hi! Checking in on task X"

# Send message to channel
slack_cli send-channel --channel-id C12345ABC --message "Weekly status update..."

# Reply in thread
slack_cli send-channel --channel-id C12345ABC --thread-ts "1234567890.123456" --message "Thanks!"

# Auto-detect (user ID creates DM, channel ID posts to channel)
slack_cli send --to U12345ABC --message "Hello!"

Commands

send-dm

Send a direct message to a Slack user.

slack_cli send-dm --user-id <USER_ID> --message "<TEXT>"

Parameters:

• --user-id: Slack user ID (starts with U, e.g., U12345ABC)
• --message: Message content (supports Slack mrkdwn formatting)

Example:

slack_cli send-dm \
  --user-id U0123456789 \
  --message "Hi! This is Oliver from DoWhiz. Can you provide an update on the authentication task?"

send-channel

Send a message to a Slack channel.

slack_cli send-channel --channel-id <CHANNEL_ID> --message "<TEXT>" [--thread-ts <TS>]

Parameters:

• --channel-id: Slack channel ID (starts with C, e.g., C12345ABC)
• --message: Message content
• --thread-ts: (Optional) Message timestamp to reply in thread

Example:

slack_cli send-channel \
  --channel-id C0123456789 \
  --message ":memo: Weekly TPM Report\n\n*Completed:* 5 tasks\n*In Progress:* 3 tasks\n*Blocked:* 1 task"

send

Auto-detect destination and send message.

slack_cli send --to <ID> --message "<TEXT>" [--thread-ts <TS>]

If --to starts with U, creates a DM. Otherwise, sends to channel.

Message Formatting

Slack supports mrkdwn formatting:

Format	Syntax	Example
Bold	*text*	*important*
Italic	_text_	_emphasis_
Strikethrough	~text~	~deleted~
Code	`code`	`variable`
Code block	```code```	Multi-line code
Link	`<URL	text>`
User mention	<@USER_ID>	<@U12345>
Channel link	<#CHANNEL_ID>	<#C12345>
Emoji	:emoji_name:	:white_check_mark:

TPM Use Cases

1. Task Follow-up

slack_cli send-dm \
  --user-id U0123456789 \
  --message "Hi! :wave: Checking in on task *API Integration*. What's your current progress?"

2. Weekly Report to Channel

slack_cli send-channel \
  --channel-id C0123456789 \
  --message ":chart_with_upwards_trend: *Weekly TPM Report - $(date +%Y-%m-%d)*

*Completed This Week:*
• Task A - Done
• Task B - Done

*In Progress:*
• Task C - 70% complete
• Task D - Starting

*Blockers:*
• Waiting on API documentation

_Reply in thread for questions._"

3. Reminder DM

slack_cli send-dm \
  --user-id U0123456789 \
  --message ":alarm_clock: Reminder: Task *Database Migration* is due tomorrow. Please update the status in Notion."

Environment Variables

Variable	Required	Description
SLACK_BOT_TOKEN	Yes	Bot OAuth token (xoxb-...)
SLACK_API_BASE_URL	No	Override API base (default: https://slack.com/api)

Error Handling

Error	Cause	Solution
channel_not_found	Invalid channel ID	Verify channel ID and bot membership
not_in_channel	Bot not in channel	Invite bot to the channel
user_not_found	Invalid user ID	Verify user ID format
cannot_dm_bot	Trying to DM a bot	Use channel instead
no_permission	Missing scopes	Check bot OAuth scopes

Required Bot Scopes

• chat:write - Send messages
• channels:read - List channels
• users:read - Look up users
• im:write - Send DMs
• groups:write - Post to private channels

Tips

1. Always confirm user IDs before sending DMs to avoid contacting wrong person
2. Use threads for follow-up messages to keep channels organized
3. Include context in messages (task name, deadline, etc.)
4. Rate limits: Slack limits ~1 message per second per channel