Where does the bug appear (feature/product)?
Somewhere else…
Describe the Bug
I created an automation, defined slack as MCP, I can see the channel list (in the automation config) but the agent fails to send the message.
Subject: Slack MCP integration failing — missing_scope error on SendSlackMessage and bot cannot join channel
Environment:
Running as a Cursor Cloud Agent (Automation, cron-triggered)
Workspace: /workspace on Linux 6.12.58+
Date of occurrence: 2026-03-09T09:16:53Z
Automation ID: 09ea2fc2-0235-4b51-ad44-93ada2f12279
Problem: The built-in Slack MCP tools (SendSlackMessage and ReadSlackMessages) are both failing. We cannot send or read messages in the configured channel #mixpanel-alerts (channel ID: C0AEZE0JGL9).
Error 1 — SendSlackMessage:
Call: SendSlackMessage({ message: “Test notification…”, channel: “#mixpanel-alerts” })
Response: An API error occurred: missing_scope
This indicates the bot token used by Cursor’s Slack integration is missing required OAuth scopes (likely chat:write).
Error 2 — ReadSlackMessages:
Call: ReadSlackMessages({ channel: “C0AEZE0JGL9”, limit: 5 })
Response: The Cursor bot could not join this channel. Please invite the Cursor bot to this channel to use it with automations.
This suggests the bot either lacks channels:join / channels:read scopes, or it simply hasn’t been invited to the channel.
Additional context:
No SLACK_* environment variables are set in the agent runtime (env | grep -i slack returns nothing).
No MCP server configuration files were found in the workspace (no .cursor/mcp*.json).
The ListMcpResources tool returned no resources.
The Slack tools appear to be built-in to the Cloud Agent runtime rather than user-configured MCP servers.
Questions for Cursor support:
Which Slack App / bot token do the built-in SendSlackMessage and ReadSlackMessages tools use? Is this managed by Cursor or do we need to configure it ourselves?
Where do we configure the OAuth scopes and bot token for this integration? Is it in the Cursor Dashboard under Cloud Agents settings, or in the Slack App at api.slack.com?
What specific OAuth scopes are required for full functionality (chat:write, channels:read, channels:history, channels:join)?
Is inviting the bot to the channel a manual step we need to do in Slack, or should the integration handle that automatically?
Are there any setup steps we may have missed during the Slack MCP onboarding?
Steps to reproduce:
Create a cron-triggered Automation that calls SendSlackMessage with any message.
Observe the missing_scope error in the agent output.
Call ReadSlackMessages on channel C0AEZE0JGL9 and observe the “bot could not join” error.
Steps to Reproduce
create an automation agent and try to send a slack message
Operating System
MacOS
Version Information
cloud agent automations
Does this stop you from using Cursor
Yes - Cursor is unusable