How to Connect Slack MCP to an AI Agent
Auth setup
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.
Key facts
| Base URL | https://slack.com/api/ |
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| 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. |
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| Token URL | https://slack.com/api/oauth.v2.access |
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| Scopes | chat:write,channels:read,channels:history,users:read |
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| Request body | application/json |
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| Pagination | cursor-based: response has 'response_metadata.next_cursor'. Pass cursor= param. Default limit 100. |
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| 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. |
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| Error format | JSON: {"ok":false,"error":"channel_not_found"}. Always check 'ok' field — HTTP status is always 200. |
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Key endpoints
| Method | Path | Description |
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| | 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 |
Quickstart
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.
Frequently Asked Questions
What is Slack MCP's AEO score?
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Slack MCP has an AEO score of 1.00 and is rated AAA (Best-in-class agent integration). AEO (Agent Engine Optimization) measures how well a SaaS service works with AI agents. Scores range from 0.00 to 1.00, with grades from AAA (best) to D (not agent-ready).
Is Slack MCP AI-agent-ready?
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Slack MCP is currently ✓ verified for AI agent use. It offers an official MCP (Model Context Protocol) server, which means AI agents can connect directly. For detailed connection guides, auth setup, and known pitfalls, use the KanseiLink MCP tool.
How does Slack MCP compare to other Communication services?
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In the Communication category, Slack MCP is rated AAA. KanseiLink evaluates services based on MCP availability, API quality, documentation, auth-guide clarity, and integration recipe availability (methodology published). Visit the full rankings at kansei-link.com to see how Slack MCP compares.
How can I integrate Slack MCP with an AI agent?
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The fastest way to integrate Slack MCP with an AI agent is through KanseiLink MCP. Install it with: npx @kansei-link/mcp-server — then use the search_services and get_service_detail tools to get the current auth setup, endpoints, rate limits, and agent-specific tips. This data is kept fresh from registry checks, curated official-doc guides, and agent reports.
How do I authenticate with Slack MCP?
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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. Setup: 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.
What are Slack MCP's API rate limits?
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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.