If you want to use a database access MCP like the Supabase one my recommendation is:
1. Configure it to be read-only. That way if an attack gets through it can't cause any damage directly to your data.
2. Be really careful what other MCPs you combine it with. Even if it's read-only, if you combine it with anything that can communicate externally - an MCP that can make HTTP requests or send emails for example - your data can be leaked.
See my post about the "lethal trifecta" for my best (of many) attempt at explaining the core underlying issue: https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/
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