How Building AI Agents Has Changed in 2026
Twelve months ago, building an AI agent meant picking a framework, defining your tools, standing up a RAG pipeline, and writing a stack of glue code to wire it all together. That was the default playbook. The post-mortem on six months of work usually went the same way: half the time went into infrastructure that had nothing to do with the agent’s actual job.
That isn’t where the work is anymore. Most of the middle layer is gone. The SDKs ship with the tools, the skills system replaced the upfront tool registry, and longer context windows pushed vector search out of the default slot it held all of last year.
The shape is the same as a lot of infrastructure shifts before it. The hard thing got cheap, the cheap thing got expected, and the question moved up a level.