Slack Outgoing Message

Formatting Rules

• Write concise Slack-ready text that follows the live tool contract plus ../slack/references/markdown.md.
• Prefer a short opener, a few tight bullets, and a clear ask or next step.
• Use explicit Slack mention syntax only when you resolved the target successfully.
• Preserve source links, code, owners, dates, and commitments unless the user asked for edits.
• Do not invent approvals, decisions, or follow-through.

Workflow

1. Identify the intended destination before drafting: channel, thread, DM, or group DM.
2. Determine the execution mode from the user's request:
   • explicit send/post/reply/share: use the direct write action
   • explicit draft/review/later-send: use the draft action
   • future delivery: use slack_schedule_message
   • canvas/doc request: use slack_create_canvas
3. Read ../slack/references/markdown.md and use that authoring contract.

Tool Guardrails

• Treat optional Slack tool parameters as absent-by-default.
• thread_ts is valid only for replies in an existing thread. For normal channel posts, DMs, and new group DMs, omit the thread_ts key entirely.
• slack_create_canvas is an immediate write, not a draft. Use it only when the user explicitly asked for a canvas, doc, or immediate Slack write of that form.
• Use slack_schedule_message only when the user explicitly asked for future delivery or supplied a send time.
• slack_send_message_draft cannot overwrite an existing attached draft, and do not claim that you verified the destination is draft-free before calling the tool.
• If slack_send_message_draft returns draft_already_exists, stop immediately. Tell the user there is already an attached draft in that destination and that Slack cannot overwrite it.
• Current Slack app support here is centered on messages, drafts, scheduled messages, canvases, and read/search flows. Do not claim support for creating channels, editing messages, deleting messages, or resolving Slack user groups when the runtime does not expose those actions.

Destination Safety

• If the user wants to cc, mention, or tag someone, first check whether that person is already in the destination channel or group DM when the connector makes that practical. If you cannot verify it, do not imply the mention will notify them.
• Treat @here, @channel, @everyone, and similar broad notifications as high-impact. Do not add them unless the user explicitly asked for them.

Mention Rules

• Resolve user mentions before writing when the message should tag a person, and use Slack mention syntax: <@U123456>.
• Resolve Slack user groups before writing only when the runtime exposes a way to do so, and use Slack mention syntax: <!subteam^S123456>.
• Do not rely on bare @name text in outgoing Slack messages.
• If you cannot resolve the correct user or group, tell the user and compose the draft or message without implying the mention will work.