Stage 2 · Lesson 4 of 7
Tool choice and parallel calls
is a request setting that controls whether the model may call tools. Auto lets it decide, which is right for . You can also force a tool call, force one named tool or turn tools off.
Some newer models no longer accept forced tool calls, so prefer a clear instruction plus strict schemas. happen when one reply contains several calls, such as checking three orders at once. Run independent calls concurrently to save time, then return all the results together in a single message. You can turn parallel calls off when steps must happen one at a time.
Common trapsplitting results from one turn across several messages, which confuses the model and quietly trains it to stop making parallel calls.
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Resources for this stage
Start with· follow one of these
- GuideFreeClaude Tool Use Documentation
Anthropic · Intermediate
Read Overview, Define tools and Handle tool calls, then follow the tutorial that grows one call into a full loop
- GuideFreeOpenAI Function Calling Guide
OpenAI · Intermediate
The same loop on the Responses API: read it after your first provider to see what is universal