Stuck on an error with Slack? GET https://kansei-link-mcp-production.up.railway.app/api/v1/ask?service=slack&error=<short message> returns any checked fixes on file and the official docs. Read-only; nothing is published. Leave secrets out of the message; for long error text, POST the same fields as JSON.
1. Create app at api.slack.com/apps. 2. Add Bot Token Scopes (chat:write, channels:read, etc.). 3. Install to workspace. 4. Copy xoxb- Bot User OAuth Token. Or use MCP: npx @anthropic/slack-mcp.
| Base URL | https://slack.com/api/ |
|---|---|
| Auth | OAuth 2.0 with Bot Token. Install Slack app to workspace, get xoxb- bot token. Include as Bearer token in Authorization header. Or use official Slack MCP server. |
| Token URL | https://slack.com/api/oauth.v2.access |
| Scopes | chat:write,channels:read,channels:history,users:read |
| Request body | application/json |
| Pagination | cursor-based: response has 'response_metadata.next_cursor'. Pass cursor= param. Default limit 100. |
| Rate limit | Tier-based: Tier 1 (1/min), Tier 2 (20/min), Tier 3 (50/min), Tier 4 (100/min). chat.postMessage is Tier 3. HTTP 429 with Retry-After. |
| Error format | JSON: {"ok":false,"error":"channel_not_found"}. Always check 'ok' field — HTTP status is always 200. |
| Method | Path | Description |
|---|---|---|
| | List public or pre-defined channels in the workspace with pagination |
| | Post a new message to a Slack channel |
| | Reply to a specific message thread in Slack |
| | Add a reaction emoji to a message |
| | Get recent messages from a channel |
| | Get all replies in a message thread |
| | Get a list of all users in the workspace with their basic profile information |
| | Get detailed profile information for a specific user |
POST /api/chat.postMessage HTTP/1.1
Host: slack.com
Authorization: Bearer xoxb-your-token
Content-Type: application/json
{"channel":"C01234567","text":"Hello from agent!"}
Response: {"ok":true,"channel":"C01234567","ts":"1234567890.123456"}Source: curated by KanseiLink from official documentation (docs) and registry checks. Last reviewed: 2026-06-09. Specs change — verify against the official docs before production use.