Slack Notifications

Package @kazuph/mcp-slack (stdio). Docs: https://api.slack.com/docs. Channel mappings: .opencastle/stack/notifications-config.md

Setup

• SLACK_MCP_XOXB_TOKEN — bot token, stored in CI/env, rotated periodically.
• SLACK_MCP_ADD_MESSAGE_TOOL=true is required to post at all — write support is off by default.
• Minimal bot scopes for notifications: chat:write, channels:read, conversations:history, users:read. Read-only: channels:read, channels:history, im:read.

Rate limits

Write 20/min, read 50/min. Batch updates instead of per-step chatter, thread rather than posting new messages, and cache channel/user IDs — repeated users_resolve lookups burn the read budget.

Tools

• conversations_add_message — channel_id, payload, content_type, thread_ts
• conversations_history — channel_id, limit
• conversations_replies — channel_id, thread_ts, limit
• users_resolve — email|username

Check the response for ok; a failed post returns error rather than throwing.

Approvals are dual-channel

Post to Slack and ask in chat. First response wins.

1. Post ⏳ Approval Required — TAS-42: <action> with reply instructions, keeping the returned thread_ts.
2. Ask the same question in chat. A chat answer wins → post the confirmation into the Slack thread.
3. Otherwise poll conversations_replies on that thread every 30s, timing out at 10 min, matching approved/yes/go vs rejected/no/stop.
4. If the session ends before a reply, write a checkpoint with channel, thread ID, question, and timestamp. The next session's on-session-start hook picks up the reply.

Always thread; one thread per task; include the tracker issue ID in every message. Never put secrets in a message body.