Tools frontmatter on do not work with toolsets that have mcp tools. Only built in work

[adriandarian]

• Copilot Chat Extension Version: latest
• VS Code Version: 1.109.5
• OS Version:
• Feature (e.g. agent/edit/ask mode): any
• Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): any
• Logs:

Steps to Reproduce:

1. Build a prompt file
2. Install any mcp
3. Create a toolset
4. List toolset in prompt file under tools frontmatter
5. Run prompt in chat
6. It won't have access to mcp tools