1. What file configures MCPs?
.claude/mcp.json in your project root.
2. Name 3 of the 6 essential MCPs:
Playwright, Supabase, Memory
3. What happens if you edit mcp.json without restarting Claude Code?
Nothing. The changes don't load until you restart. You'll sit there confused wondering why the new tool isn't showing up.
4. Why never hardcode API keys in the config?
Because if that file ever hits a repo or gets shared, your keys are exposed. One leaked key can rack up charges fast. Use env variables or a .env file that's gitignored.
(Current list of MCPs Claude code said I had 🤷♀️)