Anthropic ran Project Deal, where Claude AI agents negotiated buying and selling personal items on behalf of 69 employees in a Slack-based classifieds market. They compared outcomes between a top-tier model (Opus 4.5) and a smaller one (Haiku 4.5), finding that smarter agents secured higher prices and more deals—differences participants didn’t notice. In total, agents struck 186 deals worth just over $4,000.