LLM Function Calling and Tool Use Guide 2026

LLM Function Calling and Tool Use Guide 2026: OpenAI, Anthropic, Google

Function calling is the bridge between a language model’s text output and the real world. Instead of asking a model to guess what the weather is, you hand it a get_weather tool definition, and it decides when to call it, what arguments to pass, and how to incorporate the result. As of 2026, every major provider—OpenAI, Anthropic, and Google—supports this pattern, but the APIs look meaningfully different. This guide walks through each one with working Python code and covers parallel calls, agent loops, security, and how to pick the right approach. ...

April 27, 2026 · 19 min · baeseokjae
Gemini CLI Guide 2026: How to Use Google Gemini from the Terminal

Gemini CLI Guide 2026: How to Use Google Gemini from the Terminal

Gemini CLI is Google’s open-source terminal AI agent that gives you access to Gemini 2.5 Pro — with a 1 million token context window — for free, with no credit card required. Install it with one npm command, sign in with your Google account, and you’re ready to query, code, and automate from the terminal within 60 seconds. What Is Gemini CLI? Gemini CLI is an open-source, Apache 2.0-licensed AI agent that runs directly in your terminal, powered by Google’s Gemini models. Launched officially by Google in 2025 and now at v0.32.1 (March 2026) with Gemini 3 support, it has accumulated 96,600+ GitHub stars — making it one of the most popular developer tools in the AI ecosystem. Unlike proprietary desktop IDEs or subscription-gated copilots, Gemini CLI gives every developer free access to Gemini 2.5 Pro’s 1 million token context window at 60 requests per minute and 1,000 requests per day — the industry’s most generous free tier, with no credit card required. The tool spans a wide range of tasks: code generation, debugging, file manipulation, shell command execution, image analysis, PDF summarization, and deep research. Its open-source nature means you can inspect the code, contribute fixes, and audit exactly what happens with your data — something closed-source alternatives cannot offer. ...

April 16, 2026 · 15 min · baeseokjae