Add instructions for Copilot

Is it possible to add instructions for Copilot in VSCode?
I tried to follow instructions for Cursor in a hope that it might work for Copilot in VSCode, so I added this configuration to mcp.json:

{
	"servers": {
		"slack": {
			"url": "https://mcp.slack.com/mcp",
			"auth": {
			  "CLIENT_ID": "XXXXX.XXXXX"
			}
		}
	},
	"inputs": [
	]
}

But when I try to start the server, I get this error: Invalid client_id parameter.

Review the existing instructions for Cursor and the reported mcp.json configuration, then determine what VS Code Copilot requires for the Slack MCP server. Add clear Copilot-specific setup instructions and explain how to avoid the reported “Invalid client_id parameter” error; confirm that the documented configuration starts the server successfully.