PlugWiki

Add Slack to Cursor

Install Slack's plugin from the Cursor Marketplace or paste Slack's config, sign in, and Cursor's agent can search Slack and post as you.

Install Slack's plugin from the Cursor Marketplace, or add Slack's config with its client ID, then click Connect and sign in. Cursor's agent can then search your Slack, read channels and threads, and send messages as you. Your Slack admin has to approve Cursor first. Most problems happen at sign-in, and updating Cursor fixes many of them.

Good for

  • Developers who want Slack threads and decisions as context while they code in Cursor
  • Engineers who post release or incident updates to a channel from the editor
  • Slack admins approving Cursor for their workspace
  • Anyone stuck on a Slack sign-in error in Cursor

Add Slack to Cursor

Cursor

  1. 1

    Copy this prompt.

    Add the Slack MCP server to Cursor. Run this command:

/add-plugin slack

Then check that it loaded and tell me if I need to sign in or restart.
  2. 2

    Paste it into Cursor in agent mode. It shows the change and asks before running it.

Requires Slack workspace account, Slack admin approval.

Read-only mode: Slack has no read-only mode. Cursor asks before each Slack action by default, so leave Slack's send actions off your auto-run allowlist.

The plugin adds Slack's skills and commands as well as the server; the config file adds only the server. Keep the CLIENT_ID line if you add it by hand: without it, sign-in fails with 'does not support dynamic client registration'. After saving, click Connect and approve in the browser. Sign-in returns to Cursor on local port 8787, so close any other app using that port. If it fails, check the MCP Logs in the Output panel (Cmd+Shift+U).

From the project README. Source.

Common errors and fixes

  • Incompatible auth server: does not support dynamic client registration

    Cause: The Slack entry has no Slack client ID, or an older Cursor did not pass the plugin's ID.

    Fix: Use Slack's config with CLIENT_ID 3660753192626.8903469228982, or the Marketplace plugin, on a current Cursor.

    cursor Source

  • Slack says you are not authorized to install Cursor in your workspace

    Cause: Slack's app approval policy has Cursor denied or restricted.

    Fix: A Slack admin opens Apps & Workflows, finds Cursor under Denied apps or Restricted, and approves it.

    cursor Source

  • OAuth token exchange failed: net::ERR_FAILED, then 'Authorization session ended'

    Cause: A Cursor bug in the background process that finishes sign-in.

    Fix: Fully quit Cursor with Cmd+Q, reopen it and reconnect Slack.

    cursor Source

  • Browser shows 'File not found' on localhost:8787/callback after you click Allow

    Cause: Another app is holding port 8787, so the sign-in never reaches Cursor.

    Fix: Run lsof -nP -iTCP:8787 -sTCP:LISTEN, stop that process, update Cursor and connect again.

    cursor Source

  • Only the older Slack tools appear, with no reaction or file tools

    Cause: Slack's newer permissions are not approved for Cursor in your workspace.

    Fix: Have an admin approve Cursor's updated permissions, run Clear All MCP Tokens and reconnect.

    cursor Source

  • Must use PKCE to redirect to a non-web URI

    Cause: Slack's sign-in server rejected the request. Cursor staff said Slack shipped a fix in May 2026, but one user still saw the error afterwards.

    Fix: Update Cursor, run Clear All MCP Tokens from the command palette, restart and reconnect.

    cursor Source

  • Slack sign-in fails in the standalone Cursor Nightly app

    Cause: Slack only accepts the regular Cursor app's sign-in callback.

    Fix: Install the regular Cursor app and pick Nightly under Settings > Beta > Update Access.

    cursor Source

  • redirect_uri is not registered when signing in from the Cursor CLI

    Cause: The CLI used a sign-in callback Slack did not accept.

    Fix: Update Cursor; staff said a May 2026 update fixed CLI sign-in for Slack.

    cursor Source

Permissions

Medium risk

Cursor can send, schedule and react in Slack under your name in any conversation you can reach. Leave the approval prompt on for Slack and keep its send actions off your auto-run allowlist.

What it can do

  • Read your data
  • Create and change things
  • Delete things
  • Read-only mode

Watch out for

  • Cursor can post to Slack as you

    Messages, drafts, reactions and canvases appear under your name. Read each approval prompt before you let a send through. cursor.com

  • Auto-run skips the approval prompt

    Tools on your allowlist run without asking. Keep Slack's send and create actions off it. cursor.com

  • Your Slack admin must approve Cursor

    An admin approves Cursor in Slack under Apps & Workflows before anyone can sign in. Admins can also audit MCP activity. forum.cursor.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details
Turning on read-onlySlack has no read-only mode. Cursor asks for approval before MCP tool calls by default and follows the same Run Modes as terminal commands; keep Slack's send tools off the auto-run allowlist.
Talks tomcp.slack.com
Sign-in and keysCursor stores the Slack OAuth token after you click Connect; run Clear All MCP Tokens from the command palette to remove it.

Works in

Slack documents both the plugin and the config file for Cursor. Most problems happen at sign-in, and several have been fixed in newer Cursor versions.

Tap an app to see how to set it up and any known problems.

Questions

How do I add Slack to Cursor?

Install the Slack plugin from the Cursor Marketplace, or paste Slack's config into your mcp.json, using the install box above. Then click Connect and sign in to Slack in your browser.

Should I use the plugin or the mcp.json config?

Use the plugin if you also want Slack's skills and commands. Use the config file if you only want the server or need it in one project. Both use Slack's own app ID.

Why does Slack not show up in Cursor?

Check that Slack is turned on in Customize, then look at the MCP Logs in the Output panel (Cmd+Shift+U). If it is waiting for sign-in, click Connect. If you added it by hand, make sure the entry still has Slack's client ID.

Why does Cursor say Slack does not support dynamic client registration?

Your entry has no Slack client ID, and Slack does not let apps register themselves. Paste Slack's config from the install box, which includes the ID, and update Cursor.

Why does Slack say I'm not authorized to install Cursor?

Your workspace blocks Cursor until an admin approves it. A Slack admin opens Apps & Workflows, finds Cursor under Denied apps or Restricted, and approves it for the workspace.

Why do I only see some of Slack's tools in Cursor?

Your workspace has not approved Slack's newer permissions for Cursor. Ask an admin to approve them, run Clear All MCP Tokens from the command palette, and connect again.

Sign-in fails right after I click Allow. What do I do?

Fully quit Cursor with Cmd+Q, not just reload the window, then reconnect. If the browser shows a 404 instead, another app is using port 8787, so stop it and try again on an updated Cursor.

Does Slack work in the Cursor CLI?

Yes, on a current version. Cursor said a May 2026 update fixed the redirect_uri error the CLI showed when signing in to Slack.

Can I stop Cursor from posting to Slack?

Partly. Slack has no read-only mode, but Cursor asks before each Slack action unless you add it to your auto-run allowlist, so decline any send you did not want.

Can Cursor post in Slack Connect channels?

No. Slack's server blocks sending to channels shared with other companies, so those messages fail.

Information

updated Nov 1, 2026

DocsClaude connectors directoryConnect to ClaudeChangelogSlack Help Center guide

More on this

Sources

Docs, issue trackers and discussions this page is built from.

Show all 14
  1. docs.slack.dev · docs.slack.dev
  2. github.com · github.com
  3. cursor.com · cursor.com
  4. cursor.com · cursor.com
  5. forum.cursor.com · forum.cursor.com
  6. forum.cursor.com · forum.cursor.com
  7. forum.cursor.com · forum.cursor.com
  8. forum.cursor.com · forum.cursor.com
  9. forum.cursor.com · forum.cursor.com
  10. forum.cursor.com · forum.cursor.com
  11. forum.cursor.com · forum.cursor.com
  12. forum.cursor.com · forum.cursor.com
  13. docs.slack.dev · docs.slack.dev
  14. github.com · github.com

Updated Nov 1, 2026.