Five hard x402 payment cases for Claude Sonnet and Haiku. Without instructions, both agreed to pay in a token two swapped digits away from real USDC.
Not reliably, in our test. We put five hard x402 payment cases to Claude Sonnet and Claude Haiku, with no extra instructions. In the first one, the token contract in the seller's terms differed from real USDC on Base by two swapped digits, a lookalike USDC contract. Both models said the agent should pay, and Sonnet called the address the canonical USDC contract. In a separate case, Haiku also approved paying for a product its agent had never requested. When we loaded our skill and ran those three cases again, each answer became a refusal that named the field that was wrong.
Read the full report on AISkills402: https://aiskills402.com/blog/ai-agent-lookalike-usdc
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