This article was originally published on AI Study Room . For the full version with working code examples and related articles, visit the original post. LLM Function Calling: Complete Developer Guide with Code Examples Function calling (or "tool use") transforms an LLM from a chatbot into an agent that can take actions: query databases, send emails, create tickets, call APIs. Every major LLM provider now supports it, but the implementation details differ significantly. This guide covers how to design function schemas, handle errors, and implement reliable tool-use workflows across OpenAI, Anthropic, and Gemini. How Function Calling Works 1.…