OpenAI Responses API vs Chat Completions: What Changes for Agents?

If you've ever built a large-language-model application, you've most likely started with this endpoint:

POST /v1/chat/completions

In the era of GPT-3.5 and GPT-4, this endpoint was practically synonymous with the OpenAI API. Developers would pass in a set of messages, and the model would generate the next response based on the context.

But as applications have evolved from "chatbots" to "agents capable of invoking tools, executing tasks, and processing multimodal content," the structure of the API has also begun to change. OpenAI has introduced a more unified approach:

POST /v1/responses

This doesn't mean Chat Completions are obsolete; rather, it provides a more appropriate abstraction for the more complex workflows of agents.

Chat Completions: Conversation Messages at the Center

The core data structure of Chat Completions is messages. In each request round, the client must submit the context required for the model to understand the current task.

For example, a user...

Copyright of this story solely belongs to hackernoon.com. To see the full text click HERE