slack

Slack communication — channel selection, message formatting, threading, and workspace etiquette

Slack

Communicate effectively in Slack — pick the right channel, format messages clearly, and use threads properly.

When this applies

  • Sending messages, updates, or alerts to Slack
  • Responding to user requests that involve Slack communication
  • Looking up information in Slack channels or threads
  • Notifying teams about events, errors, or completions

Process

  1. Identify the target — channel name or user for DMs
  2. Use list_channels to find the correct channel ID if unknown
  3. Decide: new message or thread reply (see Decision Rules)
  4. Format the message using Slack mrkdwn syntax
  5. Send with send_message (new) or reply_to_thread (existing thread)
  6. Add add_reaction for acknowledgments instead of reply messages

Decision Rules

  • If responding to an existing conversation → reply_to_thread (never top-level)
  • If new topic or announcement → send_message to channel
  • If status update on ongoing work → find the original thread, reply there
  • If urgent/breaking → send to channel top-level, prefix with :rotating_light:
  • If informational only → add_reaction instead of a message (less noise)
  • If unsure which channel → search_messages for related keywords to find where the topic lives
  • If message is longer than 5 lines → use a thread with a short summary at top-level

Formatting

  • Bold: *text* — use for headers or key values
  • Code inline: `code` — use for variables, commands, file paths
  • Code block: ```code``` — use for logs, JSON, stack traces
  • Lists: start lines with • or 1.
  • Links: <https://url|display text>
  • Mentions: <@USER_ID> (get ID from get_user_profile first)
  • Channel links: <#CHANNEL_ID>

Do

  • Keep messages concise — lead with the conclusion, details in thread
  • Use threads for back-and-forth; keep channels scannable
  • Include context links (PRs, dashboards, docs) when referencing external work
  • Use reactions (:white_check_mark:, :eyes:, :thumbsup:) for lightweight acknowledgment
  • Search before asking — search_messages or get_channel_history to check if already discussed

Don't

  • Send multiple rapid messages — batch into one (Slack rate limits + notification fatigue)
  • Use @here or @channel unless explicitly asked (interrupts everyone)
  • Send raw JSON or logs without a code block (unreadable in Slack)
  • Reply top-level to a thread (breaks context for everyone following the thread)
  • Send sensitive data (keys, passwords, PII) in messages (Slack retains everything)