Gemini CLI is an open-source AI agent developed by Google that integrates the full power of Gemini models directly into your terminal environment. Released under the Apache 2.0 license, it offers developers a free tier with 60 requests/minute and 1,000 requests/day using a personal Google account. Built in TypeScript, it supports Gemini 3 models with a massive 1 million token context window, enabling deep codebase understanding and long document processing without context limitations. The tool ships with a rich set of built-in capabilities including Google Search grounding for real-time web information, file operations, shell command execution, and web content fetching — all directly from the CLI. Gemini CLI natively supports the Model Context Protocol (MCP), acting as both an MCP client and server, which enables seamless integration with the broader ecosystem of AI tools and external data sources. Since its release, Gemini CLI has accumulated over 102,000 GitHub stars, making it one of the fastest-growing open-source AI tools of 2026. It offers multiple authentication options including OAuth, API keys, and Vertex AI for enterprise deployments. The project is actively maintained with weekly stable releases, and a dedicated GitHub Actions integration allows teams to embed Gemini AI reviews and automation directly into their CI/CD pipelines. Non-interactive scripting modes with JSON output make it ideal for automation workflows.