from typing import List


def split_mtext_string(s: str, size: int = 250) -> List[str]:
    """Split the MTEXT content string into chunks of max `size`."""
    chunks = []
    pos = 0
    while True:
        chunk = s[pos : pos + size]
        if len(chunk):
            if len(chunk) < size:
                chunks.append(chunk)
                return chunks
            pos += size
            # do not split chunks at '^'
            if chunk[-1] == "^":
                chunk = chunk[:-1]
                pos -= 1
            chunks.append(chunk)
        else:
            return chunks