Agent Engineering

The Secret of Tool Calls

The model doesn't actually execute code — it just outputs structured text, and the framework code is responsible for parsing and executing it. Scroll down to automatically trace the complete call chain.

System Prompt

Tell the model which tools are available

User Question

User sends a request

Model Outputs JSON

Just text prediction — not a real call

Framework Parses + Executes

Your code is the actual executor

Result Injected into Context

tool_result appended, model continues predicting

Final Answer

Model generates a human-readable response

Core insight: The model is always just predicting text.
Tool call = text → framework parses → API → text

MESSAGE LIST · Live Trace

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