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Use ChatSyncs from Cursor’s Agent while you work.

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Before you start

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Connect

1

Check whether you already have the settings file

Cursor keeps its MCP servers in a file called mcp.json, inside a hidden .cursor folder in your home folder. In Cursor, choose File → Open File… and type the path straight into the dialog:
  • Mac: press Cmd + Shift + G, type ~/.cursor/mcp.json, and press Enter.
  • Windows: in the File name box, type %USERPROFILE%\.cursor\mcp.json and press Enter.
If the file opens, go to step 3. If it says the file doesn’t exist, do step 2.
2

No file yet? Create it

Choose File → New Text File, paste this, then File → Save As… and save it to the same path as in step 1 (~/.cursor/mcp.json on Mac, %USERPROFILE%\.cursor\mcp.json on Windows):
Then skip to step 4.
3

Already have a file? Add ChatSyncs to it

Inside "mcpServers": { … } there is one entry per server. Add the ChatSyncs entry after the last one, with a comma after the entry before it. For example, a file that already had a server called github ends up like this:
Save the file.
4

Sign in

Open Customize in Cursor’s sidebar and find chatsyncs in the MCP section. It shows that it needs you to sign in: click its sign-in (Connect) button. The label can differ between Cursor versions. The ChatSyncs connect page opens in your browser, naming Cursor as the app. Paste your API key and click Authorize.
5

Confirm

Back in Cursor, chatsyncs shows as switched on with its tools listed.

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Check it worked

Open the Agent chat and ask:
“List my WhatsApp templates.”
Cursor shows the ChatSyncs tool it wants to run and asks for your approval, then lists your templates.

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Disconnect

  • Pause it: open Customize, find chatsyncs, and switch its toggle off.
  • Remove it: uninstall it from Customize, or delete the "chatsyncs" entry from ~/.cursor/mcp.json.
To cut off every app that has your key, regenerate it.

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Frequently asked

Yes. Add a headers line, replacing YOUR_CHATSYNCS_API_KEY with your key:
The key is then stored in plain text in that file. Don’t share the file or commit it to git.
Yes. Put the same content in .cursor/mcp.json inside that project’s folder instead. If the project is shared through git, use browser sign-in there, never the headers version.
By default Cursor asks before each MCP tool runs. If you’ve set Cursor to auto-run tools, remember that ChatSyncs tools send real WhatsApp messages.

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Gotchas

  • Sign-in fails with an error mentioning redirect_uri. Older Cursor versions use a cursor:// sign-in address that ChatSyncs doesn’t accept. Update Cursor, or use the headers version in the FAQ above.
  • ChatSyncs doesn’t appear after saving. The file has a typing mistake, often a missing comma or bracket. Compare it with the examples above, save it again, and reopen Customize. Also check it was saved as mcp.json, not mcp.json.txt.
  • It appears but the Agent never uses it. Check the toggle is on, then ask with its name: “Use ChatSyncs to…”.