The original title is "How LLM Function Calling Actually Works — From Tokens to Tool Orchestration"

Short summary

Function calling is the most reliable way to get structured output from LLMs by enforcing schemas at the token-generation level. The article compares three approaches: plain text (unreliable parsing), JSON mode (valid JSON but no schema guarantee), and function calling (enforced schema). It covers the mechanics of constrained decoding and shows how models orchestrate multiple tool calls in a single turn.

• •Three methods compared: plain text, JSON mode, and function calling with schemas
• •Function calling uses constrained decoding to enforce schema at token-generation level
• •LLMs can orchestrate multiple tool calls in one turn through guided generation

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