Vercel AI SDK 6: An Agent Is Just a while Loop

Short summary

A hands-on teardown of Vercel AI SDK 6's agent abstraction using a mock model with no real LLM calls. The author demonstrates that generateText with tools alone is not an agent — it stops after one tool call. Flipping on stopWhen: stepCountIs(N) creates the repeated model→tool→model round trip that constitutes an actual agent loop, making the agent concept reducible to a single while-loop configuration.

• •generateText with tools is one-shot by default — no agent loop occurs
• •stopWhen: stepCountIs(N) enables the repeated tool-call round trip that defines an agent
• •AI SDK 6 also adds human-in-the-loop approval, stabilized structured output, and DevTools

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