The new paradigm for building powerful tools is to design them for AI models. Instead of complex GUIs, developers should create simple, well-documented command-line interfaces (CLIs). Agents can easily understand and chain these CLIs together, exponentially increasing their capabilities far more effectively than trying to navigate a human-centric UI.

As underlying AI models become more capable, the need for complex user interfaces diminishes. The team abandoned feature-rich IDEs like Cursor for Claude Code's simple terminal text box because the model's power now handles the complexity, making a minimal UI more efficient.

The enthusiastic reception for Google's Workspace CLI reveals a counter-intuitive trend: old-school Command-Line Interfaces are becoming the preferred way for AI agents to interact with software. Unlike humans, agents don't need GUIs and benefit from the CLI's deterministic, low-friction nature, avoiding the 'abstraction tax' of newer API layers.

Power users of AI agents believe the ideal user interface is not graphical but conversational. They prefer text-based interactions within existing chat apps and see voice as the ultimate endgame. The goal is an invisible assistant that operates autonomously and only prompts for input when absolutely necessary, making traditional UIs feel like friction.

While GUIs were built for humans, the terminal is more "empathetic to the machine." Coding agents are more effective using CLIs because it provides a direct, scriptable, and universal way to interact with a system's tools, leveraging vast amounts of pre-trained shell command data.

The terminal-first interface of Claude Code wasn't a deliberate design choice. It emerged organically from prototyping an API client in the terminal, which unexpectedly revealed the power of giving an AI model direct access to the same tools (like bash) that a developer uses.

At OpenAI, the first question is "Can we solve this with the model (tokens) instead of pixels?" This treats the AI as the primary design material, pushing designers to think about interaction and behavior before creating bespoke user interfaces.

When prototyping new AI-powered ideas, build them as command-line interface (CLI) tools instead of web apps. The constrained UI of the terminal forces you to focus on the core workflow and logic, preventing distraction from visual design and enabling faster shipping of a functional version.

OpenAI's Codex bets on a single, unified interface where the AI handles any task from one input, reducing friction. Conversely, Anthropic's Claude app bets that different work modes (Chat, Cowork, Code) are distinct enough to require separate, specialized interfaces, akin to traditional native apps.