With OpenAI’s announcement to deprecate the Assistant API, I’ve been migrating my applications to the Responses API. This transition has been quite interesting and I wanted to share some insights with the community.
What I Liked About the Assistant API
The Assistant API’s abstractions were genuinely helpful - concepts like run and thread made development straightforward and removed a lot of boilerplate. It was particularly good for getting started quickly with conversational applications.
Why the Responses API Makes Sense
After working with both APIs, I believe the deprecation stems from the Assistant API’s limited flexibility for diverse agentic use cases. While the abstractions were convenient, they also created constraints that didn’t scale well for more complex, production-ready applications.
I’ve been particularly interested in how function calling differs between these APIs, as it’s often a critical component in agentic workflows. The differences are quite significant and reveal a lot about OpenAI’s strategic direction.
I documented my analysis for function calling in a post: Migrating OpenAI Assistant API
For those going through a similar migration, I’d love to hear about your experiences. What challenges have you encountered? What benefits have you discovered with the Responses API?
Has anyone else found specific use cases where the Responses API’s flexibility has opened up new possibilities that weren’t feasible with the Assistant API?