A benchmark reveals vision agents are 45x more expensive than structured APIs for AI task execution. Teams default to vision agents not because they're better, but because building APIs requires separate engineering work across internal tools. The test compared Claude Sonnet controlling a React admin panel through screenshots versus HTTP endpoints, revealing fundamental architectural differences.

The vision agent struggled with pagination, missing reviews below the visible fold. With a 14-step walkthrough, it completed the task but consumed half a million tokens over 14 minutes. Vision results showed high variance - 749-1257 seconds across trials - while API agents maintained consistent 8-tool-call performance.

The cost difference stems from architecture: vision agents must render every intermediate state to interpret pixels, while API agents read structured responses directly. With tools like Reflex 0.9 auto-generating HTTP endpoints, API engineering costs approach zero. Vision agents remain necessary for third-party systems, but for internal tools, the new math favors structured interfaces.