Connect
Optimize
Secure
Slack MCP Server
for AI Agents
Production-ready Slack MCP server with 38 extensible actions — plus built-in authentication, security, and optimized execution.
Slack MCP Server
Built by 
StackOne
StackOne 
Coverage
38 Agent Actions
Create, read, update, and delete across Slack — and extend your agent's capabilities with custom actions.
Authentication
Agent Tool Authentication
Per-user OAuth in one call. Your Slack MCP server gets session-scoped tokens with zero credentials stored on your infra.
Agent Auth →
Security
Agent Protection
Every Slack tool response scanned for prompt injection in milliseconds — 88.7% accuracy, all running on CPU.
Prompt Injection Defense →
Performance
Max Agent Context. Min Cost.
Free up to 96% of your agent's context window to enhance reasoning and reduce cost, on every Slack call.
Tools Discovery →What is the Slack MCP Server?
A Slack MCP server lets AI agents read and write Slack data through the Model Context Protocol — Anthropic's open standard for connecting LLMs to external tools. StackOne's Slack MCP server ships with 38 pre-built actions, fully extensible via the Connector Builder — plus managed authentication, prompt injection defense, and optimized agent context. Connect it from MCP clients like Claude Desktop, Cursor, and VS Code, or from agent frameworks like OpenAI Agents SDK, LangChain, and Vercel AI SDK.
All Slack MCP Tools and Actions
Every action from Slack's API, ready for your agent. Create, read, update, and delete — scoped to exactly what you need.
Conversations
- Create Conversation
Create a new conversation (channel)
- List Conversations
List all conversations (channels, groups, DMs) from Slack and find channel IDs by name
- Get Conversation
Get details of a specific conversation
Files
- List Files
List files for a team, channel, or user
- Get File
Get detailed information about a file
- Delete File
Delete a file from Slack
Messages
- Send Message
Send a message to a channel or conversation
- List Messages
List messages from a conversation
- Update Message
Update an existing message
- Delete Message
Delete a message
Scheduled Messages
- List Scheduled Messages
List all scheduled messages
- Delete Scheduled Message
Delete a scheduled message
Users
- List Users
List all users in the Slack workspace and find user IDs by name or email
- Get User
Get details of a specific user
User Profiles
- Get User Profile
Retrieve a user's profile information including status text and emoji, title, phone, and custom profile fields
- Set User Profile
Update a user's profile information
User Presences
- Get User Presence
Get the presence of a user
- Set User Presence
Manually set the user's presence
Other (20)
- Send Ephemeral Message
Send a private temporary message visible only to a specific user in a channel (use for private welcome notes, warnings, or notifications)
- List Conversation Members
List all members of a conversation
- List Thread Replies
Retrieve a thread of messages posted to a conversation
- List Slack Connect Invites
List shared channel invites that have been generated or received
- Get File Upload URL
Get an external URL to upload a file to Slack
- Get Message Permalink
Get a permanent link to a message
- List User Conversations
List conversations a user is a member of
- Get User By Email
Get user details by email address (use to find user ID from email)
- Remove User From Conversation
Remove a user from a conversation
- Join Conversation
Join an existing conversation (use before sending messages to new channels)
- Leave Conversation
Leave a conversation
- Rename Conversation
Rename a conversation
- Invite Users To Conversation
Invite users to a conversation
- Invite Shared Conversation
Send an invitation to a Slack Connect channel
- Open Conversation
Open or resume a direct message or multi-person direct message
- Complete File Upload
Complete an external file upload and optionally share to channels
- Share File Public URL
Create a public URL for a file
- Revoke File Public URL
Revoke public sharing for a file
- Schedule Message
Schedule a message to be sent at a specific time
- Lookup Discoverable Contact
Check if an email is discoverable on Slack
Set Up Your Slack MCP Server in Minutes
One endpoint. Any framework. Your agent is talking to Slack in under 10 lines of code.
MCP Clients
Agent Frameworks
JSON{
"mcpServers": {
"stackone": {
"command": "npx",
"args": [
"-y",
"mcp-remote@latest",
"https://api.stackone.com/mcp?x-account-id=<account_id>",
"--header",
"Authorization: Basic <YOUR_BASE64_TOKEN>"
]
}
}
}Slack MCP Server Resources
MCP Code Mode: Keeping Tool Responses Out of Agent Context
Anthropic's code_execution processes data already in context. Custom MCP code mode keeps raw tool responses in a sandbox. 14K tokens vs 500.
11 min
Comparing BM25, TF-IDF, and Hybrid Search for MCP Tool Discovery
Benchmarking BM25, TF-IDF, and hybrid search for MCP tool discovery across 916 tools. The 80/20 TF-IDF/BM25 hybrid hits 21% Top-1 accuracy in under 1ms.
10 min
Indirect Prompt Injection Defense for MCP Tools: A Technical Guide
MCP tools that read emails, CRM records, and tickets are indirect prompt injection vectors. Here's how we built a two-tier defense that scans tool results in ~11ms.
12 min
Slack MCP Server FAQ
Slack MCP server vs direct API integration — what's the difference?
A Slack MCP server and direct API integration serve different use cases. Direct API integration is for software-to-software — backend code calling Slack. A Slack MCP server is for AI agents — MCP clients like Claude and Cursor, plus framework agents built with OpenAI, LangChain, or Vercel AI — discovering and calling Slack at runtime. StackOne provides both.
How does Slack authentication work for AI agents?
Slack authentication for AI agents works through a StackOne Connect Session. Create one via the dashboard or the SDK — you get an auth link and ready-to-paste config for Claude Desktop, Cursor, and other MCP clients. Your user authenticates their own Slack account; StackOne handles token exchange, storage, and refresh. Credentials never reach the LLM, and each user is isolated via
origin_owner_id.Are Slack MCP tools vulnerable to prompt injection?
Yes — Slack MCP tools can be vulnerable to indirect prompt injection. Any tool that reads user-written content — documents, messages, tickets, records, or free-text fields — is a potential vector. StackOne Defender scans every tool response before it enters the agent's context — regex patterns in ~1ms, then a MiniLM classifier in ~4ms. 88.7% accuracy, CPU-only.
What is the context bloat of a Slack agent and how do I avoid it?
Context bloat happens when Slack tool schemas and API responses eat your Slack agent's memory, preventing it from reasoning effectively. A single Slack query can return a massive JSON response, and connecting multiple tools compounds the problem. Tools Discovery and Code Mode reduce context bloat — loading only relevant tools per query and keeping raw responses out of the agent's context.
Can I limit which actions my Slack agent can access?
Yes — you can limit which actions your Slack agent can access directly from the StackOne dashboard. Toggle actions on or off, or restrict them to specific accounts, with no code changes to your agent. Session tokens can be scoped to exact actions so if one leaks, exposure stays contained.
Can I create custom agent actions for my Slack MCP server?
Yes — you can create custom agent actions for your Slack MCP server using Connector Builder. It's an integration agent your coding assistant (Claude Code, Cursor, or Copilot) can invoke to research Slack's API, generate production-ready connector YAML, test against the live API, and validate before you ship.
When should I NOT use a Slack MCP server?
Skip a Slack MCP server if your integration is purely software-to-software — direct Slack API integration is simpler when no AI agent is involved. For deterministic, compliance-critical operations (financial transactions, regulatory reporting), direct API gives you predictable behavior without agent-driven decision-making. MCP shines when AI agents need to dynamically discover and call Slack actions at runtime.
What AI frameworks and AI clients does the StackOne Slack MCP server support?
The StackOne Slack MCP server supports both. MCP clients (paste-and-go apps): Claude Desktop, Claude Code, Cursor, VS Code, Goose. Agent frameworks (code SDKs you build with): OpenAI Agents SDK, Anthropic, Vercel AI, Google ADK, CrewAI, Pydantic AI, LangChain, LangGraph, Azure AI Foundry.
Put your AI agents to work
All the tools you need to build and scale AI agent integrations, with best-in-class connectivity, execution, and security.