"""Normalize an MCP server URL.

This function processes a given URL to ensure it ends with the `/mcp/` suffix. The function handles three specific cases:
1. If the URL already ends with `/mcp` or `/mcp/`, it ensures the URL ends with `/mcp/`.
2. If the URL ends with `/sse`, it replaces `/sse` with `/mcp/`.
3. For all other cases, it appends `/mcp/` to the URL.

Args:
    url (str): The input server URL to be normalized.

Returns:
    str: The normalized MCP URL, ensuring it ends with `/mcp/`.

Examples:
    >>> convert_url("http://localhost:4444/servers/uuid")
    'http://localhost:4444/servers/uuid/mcp/'
    >>> convert_url("http://localhost:4444/servers/uuid/sse")
    'http://localhost:4444/servers/uuid/mcp/'
    >>> convert_url("http://localhost:4444/servers/uuid/mcp")
    'http://localhost:4444/servers/uuid/mcp/'
"""
You should write code starting with:
def convert_url(url: str) -> str:
    # TODO: Implement this function based on the docstring.
    pass

