Slack automation failing with missing_scope error

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Background Agent (GitHub, Slack, Web, Linear)

Describe the Bug

Hi everyone,

We’re experiencing an issue with Slack integrations in Cursor automations.

Whenever our automations attempt to send a Slack message, the following error occurs:

Failed to send Slack message
An API error occurred: missing_scope

What we’ve already tried:

Reconfigured the Slack integration multiple times

Removed the Slack bot from the workspace and installed it again

Reconnected the Slack account inside Cursor

Regenerated tokens and repeated the OAuth authorization flow

Despite this, the error still happens consistently when the automation runs.

From Slack’s documentation, missing_scope usually indicates that the token being used does not have the required permission scopes. However, since the integration is managed through Cursor, we’re unsure which scopes are actually required or if the token being used internally is missing something.

Steps to Reproduce

Just create an automation with slack

Expected Behavior

Send a message on slack

Operating System

MacOS

Version Information

On cursor.com

Does this stop you from using Cursor

Yes - Cursor is unusable

3

Hey, thanks for the detailed report and for all the troubleshooting you’ve already done.

This looks like a bug on our side. The OAuth token used by automations may be missing the required scopes to send Slack messages. Since those scopes are handled by our OAuth flow, there isn’t much you can do on your end.

To help us investigate, could you share a couple of things?

  1. A request ID from a failed automation run (you can find it in the automation run details on cursor.com)
  2. Is the target Slack channel public or private?
  3. Did this ever work before, or has it been broken from the start?

Sorry about the disruption.

4

Same issue here

  1. `bc-e157a311-98e1-40c9-9c59-1bf637c6f1f5`
  2. public
  3. Broken from the start
5

Also seeing this:

  1. bc-067b0c5b-2602-49c4-a795-e2eee274e2a3
  2. public
  3. Broken from start
6

Also seeing this:

  • bc-34477ae7-5e79-4934-99b1-6633325189be
  • public
  • broken from the start
7

same issue, and details as everyone above on bc-c65bb268-8280-4986-afb9-cb1e8a7a1961.

This is happening on the CI Failures investigation template.

10

Same issue:

  1. bc-4e58f67c-4052-4d33-adf5-4918cabb85ef
  2. public slack channel
  3. broken from the start
11
  1. bc-98958a2f-2501-42fd-88e3-0cf86d066668
  2. Public
  3. broken from the start

Thanks!

12

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

13

I was also getting the same error until I added the Cursor App in the intended channel. After adding it, it worked without any problems.

1 Like
16

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