slack-mcp-server
Slack MCP server exposing Slack Web API capabilities as MCP tools, supporting both local stdio transport and remote HTTP transport.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Tokens are provided via environment variables. README does not describe server-side request authentication/authorization for the MCP interface, transport security for HTTP mode (beyond using localhost), OAuth scopes/least-privilege, audit logging, or how errors are sanitized. Safe search appears to be enforced server-side for search, reducing accidental exposure of private content, but write tools remain powerful.
⚡ Reliability
Best When
You want an MCP-compatible integration to let an AI agent read and/or act in a Slack workspace using standardized tool calls.
Avoid When
You cannot safely handle OAuth tokens or you lack control over what the agent is allowed to do (e.g., broad write capabilities like posting/reactions/search across the workspace).
Use Cases
- • List Slack channels with pagination
- • Post messages and reply within Slack threads
- • Add reactions to Slack messages
- • Fetch channel history and thread replies
- • Retrieve Slack user profiles (single and batch)
- • Search Slack messages with filters (including safe-search option)
Not For
- • Automating Slack actions without obtaining/securely storing Slack OAuth tokens
- • Workloads that require strict tenant isolation or strong per-request authorization beyond what the server implements
- • High-scale deployments without verified rate-limit handling
Interface
Authentication
Server requires Slack OAuth tokens via environment variables. README does not document specific OAuth scopes or least-privilege guidance.
Pricing
This package is distributed via npm; costs mainly come from your Slack app usage/quotas and hosting (if using HTTP transport).
Agent Metadata
Known Gotchas
- ⚠ Write-capable tools (post message, add reaction, reply) may have side effects; agents should implement their own safeguards (confirmations, idempotency via message dedupe, etc.).
- ⚠ Message search may depend on Slack user token and safe-search behavior; agents should expect different results depending on token and SLACK_SAFE_SEARCH setting.
- ⚠ HTTP transport is started locally on a port; ensure networking/auth boundaries around the server since the README does not describe additional request authentication.
Alternatives
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Scores are editorial opinions as of 2026-03-30.