AI Coding Tools 2026: Codex, Gemini CLI, Claude Code and How to Choose
Three kinds of AI coding tools (autocomplete, AI IDEs and coding agents), how to choose for your work, a workflow that holds up, and the risks to watch.
Picture two days in the life of the same developer. On day one he writes a new API file by file, switching back and forth to Stack Overflow. On day two he describes what he needs to an AI, lets it draft the code and tests, and spends most of his time reviewing and making design decisions. The output is similar, but the skills used are very different. That is what AI coding tools are changing.
What are AI coding tools?
They are tools that use language models to help write, read, fix and explain code. There is evidence they help with certain tasks. In a GitHub controlled experiment where 95 developers wrote an HTTP server in JavaScript, the group using GitHub Copilot finished about 55% faster than the group without it. GitHub itself noted that effects on code quality still needed study, so the figure does not mean every task speeds up equally.
Three kinds of tools
1. Autocomplete in the editor
GitHub Copilot is the best-known example. It suggests code as you type in editors like VS Code. It suits repetitive work such as boilerplate, test cases or data transformation, and you still control every line.
2. AI IDEs that talk to the whole project
Cursor is an editor with AI built in. You can chat with the codebase, ask where a function is called, or request multi-file edits and review the diff before accepting. It suits refactoring and understanding unfamiliar code.
3. Coding agents in the terminal
These tools take plain-language instructions, then read files, write code, run commands and fix things until tests pass. Popular ones include OpenAI Codex CLI, Anthropic's Claude Code and Google's Gemini CLI, which Google launched in 2025 as open source with a free tier for personal Google accounts. Free-use terms for each change over time, so check the official pages before relying on them.
If you want guided practice, see the courses installing and using Gemini CLI for free, Gemini CLI for beginners, Codex CLI for beginners and installing Codex in VS Code.
Which one should you use?
- Just learning to code: start with autocomplete or a chat that explains code so you learn along the way. Do not start with an agent that does everything.
- Working in a large project: an AI IDE or an agent that reads the whole repo helps with searching and cross-file edits.
- Repetitive work with clear tests: terminal agents fit best because they can run tests and iterate on their own.
- Not a developer: agent-first platforms such as Lovable or Bolt let you build web apps from prompts, but you still need basic understanding of data and access permissions.
A workflow that holds up
- Write a clear brief first: state the goal, relevant files, constraints and how to check it is done, such as all tests passing.
- Ask for a plan before changes: have the AI summarise its plan in steps, and review it before it edits code.
- Break work into small pieces: one instruction per reviewable change. See more in prompt patterns for vibe coding.
- Read every diff: understand every line before committing. If you cannot explain it, ask the AI until you can.
- Let tests decide: have the AI write tests too, and actually run them every time.
Risks to watch
- Code that looks right but is wrong: AI may call libraries that do not exist or write logic that passes simple tests but breaks on real cases.
- Security: do not give an agent access to secrets or production databases unless necessary, and watch for prompt injection from files or web pages it reads. Read more in what prompt injection is.
- Company policy: check whether your organisation allows sending code to external AI services.
- Losing core skills: if AI does everything, you will not know how to debug when it fails.
AI writes code fast, but the person who decides which code belongs in the system still has to be you.
Pick one tool, try it on small tasks for a week, then expand. Find more AI coding courses on Plants.work Learn, and if you want to put this skill to work, browse developer roles on job search on Plants.work.