$re = '/(?:<|tool▁calls▁begin|>|<|tool_calls_begin|>|<|tool calls begin|>|<|tool\\\\\\\\_calls\\\\\\\\_begin|>|<|tool▁calls|>)/m';
$str = '<|tool▁calls▁begin|><|tool▁call▁begin|>get_time<|tool▁sep|>{"city": "Tokyo"}<|tool▁call▁end|><|tool▁calls▁end|>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php