Frameworks
What each framework solves, its abstraction level, weaknesses — and Option 0: no framework.
Frameworks: What They Abstract and What It Costs
Agent frameworks package prompt templates, tool registries, loops, state graphs, memory and tracing; the abstraction saves boilerplate and costs visibility, and the right choice depends on which you need more.
Option 0: No Framework
An LLM SDK plus ordinary application code covers most production agent systems; a tool-calling loop with a step limit is about forty lines, and you own every one of them.