The power of tools like Claude Code comes from giving the AI access to fundamental command-line tools (e.g., `bash`, `grep`). This allows the AI to compose novel solutions and lets product teams define new features using simple English prompts rather than hard-coded logic.

Claude Code's terminal-based interaction within a specific folder allows it to automatically read and reference local files. This makes "context engineering" drastically faster and more powerful than manually pasting information into a traditional chat interface, as the context is implicitly understood.

Codex lacks a built-in feature for parallel sub-agents like Claude Code. The workaround is to instruct the main Codex instance to write a script that launches multiple, separate terminal sessions of itself. Each session handles a sub-task in parallel, and the main instance aggregates the results.

The best UI for an AI tool is a direct function of the underlying model's power. A more capable model unlocks more autonomous 'form factors.' For example, the sudden rise of CLI agents was only possible once models like Claude 3 became capable enough to reliably handle multi-step tasks.

Codex exposes every command and step, giving engineers granular control. Claude Code abstracts away complexity with a simpler UI, guessing user intent more often. This reflects a fundamental design difference: precision for technical users versus ease-of-use for non-technical ones.

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.

The best agentic UX isn't a generic chat overlay. Instead, identify where users struggle with complex inputs like formulas or code. Replace these friction points with a native, natural language interface that directly integrates the AI into the core product workflow, making it feel seamless and powerful.

Codex constantly asks for permissions, which slows down complex tasks. Using the `--yolo` command-line flag bypasses all approval prompts, allowing it to run uninterrupted. While this grants full access and carries some risk, it's a critical hack for improving workflow efficiency.

Codex lacks formal custom commands. You can achieve the same result by storing detailed prompts and templates in local files (e.g., meeting summaries, PRD structures). Reference these files with the '@' symbol in your prompts to apply consistent instructions and formatting to your tasks.