CLI vs IDE vs cloud AI agents: which kind of harness is right for you?
AI harnesses come in three shapes. CLI agents (Claude Code, Codex, Aider) live in the terminal and reward scripting. IDE agents (Cursor, Windsurf, Copilot, Cline) work inside your editor with inline diffs and the lowest friction. Cloud agents (Devin, OpenHands Cloud, Replit) run on remote machines, so you can delegate a task and walk away.
Every AI coding harness lives somewhere, and where it lives changes how it feels to use more than most people expect. There are three homes: the terminal, your editor, and the cloud. Pick the one that matches how you already work and half the harness decision is made.
The three shapes, quickly
| Form factor | Where it runs | Strengths | Watch out for | Examples |
|---|---|---|---|---|
| CLI | Your terminal | Scriptable, powerful, scales to big jobs | Steeper if you’re not terminal-comfortable | Claude Code, Codex CLI, Aider, Amp |
| IDE | Inside your editor | Lowest friction, inline diffs, visual | Tied to one editor’s window | Cursor, Windsurf, Copilot, Cline |
| Cloud | A remote machine | Delegate and walk away, parallel tasks | Less visibility, your code leaves your machine | Devin, OpenHands Cloud, Replit Agent |
CLI agents: the terminal
A command-line harness runs in your shell. You type a request, it reads your project, makes edits, runs commands, and reports back, all in text. Claude Code, OpenAI’s Codex CLI, Aider, and Sourcegraph’s Amp all live here.
The reason people who like the terminal really like these is scriptability. A CLI agent slots into the same place you already chain commands, pipe output, and automate things. You can run it in a loop, wire it into a build step, or kick off a long job and let it churn. Claude Code leans all the way into this with subagents and hooks. Aider stays lean and git-native.
The cost is the obvious one. If the terminal isn’t where you’re comfortable, a CLI agent asks more of you up front. No visual diff to glance at, no buttons. Just text and your own command-line fluency.
IDE agents: your editor
An IDE harness lives inside the editor you already write code in. Cursor (a VS Code fork), Windsurf (its own AI-native editor), GitHub Copilot (across VS Code, JetBrains, and more), and Cline (an extension that drops into many editors) all work this way.
This is the lowest-friction shape, and it’s why most people start here. You see proposed changes as inline diffs, accept or reject them with a keystroke, and never leave the file you’re working in. The autocomplete is right there as you type. For anyone who thinks in files and diffs rather than shell commands, an IDE agent feels natural from the first minute.
The trade is that you’re working inside one editor’s window. That’s usually fine, since it’s where the work is anyway, but it doesn’t have the same “automate it and walk away” character a CLI tool has. It’s an assistant at your shoulder, not a process you set running in the background.
Cloud agents: hand it off
A cloud harness runs on a remote machine, not yours. You give it a task, often through Slack, a GitHub issue, or a web interface, and it sets up an environment, does the work on its own, and comes back with a result, frequently a pull request. Devin, OpenHands Cloud, and Replit Agent are the names here.
This is the “delegate and walk away” shape. You’re not watching every step; you’re assigning a ticket the way you might to a teammate, and several can run in parallel. For well-scoped tasks, that’s a genuine multiplier. Replit’s version even builds and deploys a full app from the browser, which is why it appeals to people who aren’t traditional developers at all.
Two things to weigh. You get less moment-to-moment visibility. You see the outcome more than the process, so a task that goes sideways can burn time before you notice. And your code runs on someone else’s machine, which matters a lot for anything private or regulated. Self-hostable options like OpenHands exist precisely so you can get the delegate-and-walk-away model without sending code off your own infrastructure.
Which one fits you
If you live in the terminal and like to script, start with a CLI agent. Claude Code or Aider, depending on whether you want a polished kit or a transparent git-native one.
If you write code in an editor and want the gentlest on-ramp, an IDE agent is the answer. Cursor or Cline if you want model choice, Copilot if you’re already on GitHub.
If you want to assign whole tasks and get results back without supervising each step, look at cloud agents. Devin if you have budget, OpenHands if you’d rather self-host, Replit if you’re building from scratch and not a developer by trade.
None of this picks your model for you. Most harnesses in all three shapes can run the top models. And plenty of tools blur the lines: Claude Code is CLI-first but also has IDE and web surfaces, and Cursor pairs an editor with cloud agents. Use the form factor as your starting filter, then narrow with the full harness comparison.
Common questions
- What's the difference between a CLI and an IDE AI agent?
- A CLI agent runs in your terminal and is built for scripting and command-line workflows, like Claude Code or Aider. An IDE agent runs inside your code editor with inline diffs and the lowest friction, like Cursor or Cline. Same idea, different home.
- What is a cloud AI coding agent?
- A cloud agent runs on a remote machine instead of your computer. You hand it a task, often through Slack or a GitHub issue, and it works on its own and reports back. Devin, OpenHands Cloud, and Replit Agent are examples.
- Which form factor is easiest for a beginner?
- An IDE agent like Cursor, or a cloud builder like Replit Agent if you're not a developer. Both hide the terminal and show you what's happening on screen, which is a gentler start than wiring up a command-line tool.