GuzzleHttp + POST + PHP +路径

I need some help. I am developing a post in PHP with GuzzleHttp. My URL is this -> 'http://qql/accountv2/schools/{id}/users', I need to pass one id on path, my code is below:

$URLAccV2Ssc = http://qql/accountv2/schools/{id}/users;
$idSchool = 123;        
        $responseSSC = $client->post($URLAccV2Ssc, [
            'form_params' => [
                "id" => $idSchool,
                "userId" => $user->getUUID(),
                "registry" => "string",
                "activeRegistry" => true

            ],
            'headers' => [
                'Authorization' => 'Bearer ' . $bearerTokenAccV2,
                'Content-type' => 'application/json'
            ]
        ]);

The error that I have is this -> ["The value '{id}' is not valid for Guid.","Unexpected character encountered while parsing value: i. Path ''

Can someone help me please? Thanks.