The Control Surface
The problem
The first design decision is not which framework to adopt, but where to place control. Anthropic distinguishes workflows, whose paths are specified in code, from agents, whose models decide how to proceed. Its recommendation is deliberately conservative: begin with the simplest system that can work, and introduce autonomy only when the task’s structure genuinely requires it.
Hugging Face’s account makes the same boundary concrete by describing agency as a spectrum: a model may choose a route, select a tool, or control an entire loop. Its ReAct examples show why memory, parsers, error handling, and retry logic appear as soon as the model controls program flow. OpenAI’s platform launch complicates the picture from another direction: APIs now package multi-turn tool use, computer interaction, orchestration, and observability as standard building blocks.
Together, these readings ask whether “agent” names a fundamentally new architecture or a familiar program with a model-controlled control surface. That distinction matters because every increase in model authority trades predictability for flexibility, and the next session examines the interfaces on which that trade depends.
Readings