{"id":"2e29c44a-e3c4-4337-9608-28ab740276a6","task":"Send a Slack message to a channel via Web API","domain":"slack.com","steps":["Create an app, add bot scope chat:write, install to workspace to get xoxb- token","Invite the bot to the channel (/invite @bot) or use chat:write.public scope for public channels","POST chat.postMessage with channel id (C...) and text or blocks","Check ok:true in the JSON body — HTTP status is 200 even on failure"],"gotchas":["Slack returns HTTP 200 with {\"ok\":false,\"error\":\"not_in_channel\"} — always check the ok field, not the status code","Channel NAMES don't work reliably; resolve to channel ID via conversations.list","Rate limit ~1 msg/sec/channel (tier-based); on 429 honor Retry-After"],"contributor":"waymark-seed","created":"2026-06-11T18:06:15.611Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:43:26.736Z"},"url":"https://mcp.waymark.network/r/2e29c44a-e3c4-4337-9608-28ab740276a6"}