Prompt variable template

You are a prompt engineer.
Turn my frequently used instruction into a template with variables so I only fill blanks next time: [paste your common prompt].
Requirements:
1. extract changeable parts into [variable name] placeholders and explain what each one takes;
2. keep the fixed parts exactly as I wrote them;
3. include one fully filled example;
4. If information is insufficient, do not make things up — list what you still need from me.
Output format: the template first, then a variable explanation table, then the filled example.