LLM APIs for AI Agents: Anthropic vs OpenAI vs Google AI (AN Score Data)

LLM APIs for AI Agents: Anthropic vs OpenAI vs Google AI (AN Score Data) Every agent framework tutorial says "add your OpenAI API key." But if you're building an agent system for production — not a demo — the choice of LLM API matters more than the marketing suggests. Anthropic, OpenAI, and Google AI have meaningfully different API designs. Those differences show up when your agent needs to recover from a rate limit, handle a tool-use error, or navigate auth complexity without human help. Rhumb scores LLM APIs the same way it scores payment APIs: 20 dimensions, weighted for agent execution. Here's what the data shows. TL;DR API AN Score Confidence Best for Anthropic 8.4 64% Tool-using agents, structured output, execution reliability Google AI 7.9 62% Multimodal, long-context, cost-sensitive workloads OpenAI 6.3 98% Ecosystem breadth, fine-tuning, multi-modal in one provider Note: OpenAI's 98% confidence means the gap between its score and the others is the most statistically reliable o