Scan of 2,500 MCP servers: 72 touch money, none documents a kill switch

A scan of 2,500 public MCP servers found 72 that move funds through payments, transfers, trading or treasury, yet none documents a way to stop them mid-flight. The authors propose three controls: a hard spending ceiling kept outside the agent's context, signed receipts, and a stop checked on the same path as the budget.

• 72 of 2,500 public MCP servers perform financial operations
• None of them documents a kill switch
• Spending ceilings must live outside the agent's context and run before the side effect
• Receipts are signed over RFC 8785 canonical JSON and verify without the server