Slack Send Message

Slack Send Message

When to Use

• User asks to "send a message" or "post in channel"
• User asks to "DM someone" or "message someone"
• User asks to "reply to" a message or thread
• User wants to "post in #channel"

Tools

Discovery

• SLACK_FIND_CHANNELS — Search channels by name
• SLACK_LIST_ALL_CHANNELS — List all channels
• SLACK_FIND_USERS — Search users by name
• SLACK_FIND_USER_BY_EMAIL_ADDRESS — Find user by email
• SLACK_OPEN_DM — Open/get DM channel with a user

Context

• SLACK_FETCH_CONVERSATION_HISTORY — Get recent channel messages
• SLACK_FETCH_MESSAGE_THREAD_FROM_A_CONVERSATION — Get thread replies
• SLACK_SEARCH_MESSAGES — Search messages with query modifiers

Messaging

• SLACK_SEND_MESSAGE — Send message to channel/DM
  • channel: Channel or DM ID
  • text: Message content
  • thread_ts: Thread timestamp (for replies)
• SLACK_ADD_REACTION_TO_AN_ITEM — React with emoji

Workflow

Step 1: Discover the Target (NEVER assume IDs)

For channels:

SLACK_FIND_CHANNELS(query="engineering")

For users:

SLACK_FIND_USERS(search_query="Sarah")

If multiple matches, ask user to clarify.

Step 2: Read Before Writing

Understand the conversation context before sending:

For channel messages:

SLACK_FETCH_CONVERSATION_HISTORY(channel=channel_id, limit=20)

For thread replies:

SLACK_FETCH_MESSAGE_THREAD_FROM_A_CONVERSATION(channel=channel_id, thread_ts=message_ts)

This helps you:

• Avoid repeating what was just discussed
• Reference recent messages naturally
• Match the channel's tone and formality

Step 3: Craft Contextual Message

Based on what you've read:

• Reference relevant recent discussion
• Match the channel's communication style
• Keep messages concise but complete
• Use Slack formatting: bold, _italic_, code, triple-backtick code blocks, >quotes

Step 4: Send

Channel message:

SLACK_SEND_MESSAGE(channel=channel_id, text="Message here")

Thread reply:

SLACK_SEND_MESSAGE(channel=channel_id, text="Reply here", thread_ts=thread_ts)

DM workflow:

1. SLACK_FIND_USERS(search_query="Bob")
2. SLACK_OPEN_DM(users=user_id)
3. SLACK_SEND_MESSAGE(channel=dm_channel_id, text="Hey Bob...")

Step 5: Quick Acknowledgments

When a reaction is more appropriate than a text reply:

SLACK_ADD_REACTION_TO_AN_ITEM(channel=channel_id, timestamp=message_ts, name="thumbsup")

Use reactions for: acknowledgments, approvals, celebrations (🎉), simple yes/no.

Important Rules

1. Never assume IDs — Always discover channels and users first
2. Read before writing — Fetch recent context for better messages
3. Thread replies stay in thread — Use thread_ts for threaded conversations
4. DMs need OPEN_DM first — Can't send DM without opening the channel
5. Reactions over text — Use emoji reactions for simple acknowledgments