How to Use Cline: The Beginner's Guide (First Task, Plan vs Act, Rules, and the Approve-Every-Diff Rule)
CodexFuse Team · 2026-10-30T11:27:12.874Z · 11 min read min read
How to use Cline, the open-source AI coding agent for VS Code: install it, pick a model, master Plan and Act modes, write .clinerules, and approve every diff. Complete beginner guide, 2026.
What is Cline?
Learning how to use Cline starts with understanding what it is: an open-source AI coding agent that lives inside your editor — primarily VS Code — and carries out multi-step coding tasks on your behalf. Unlike a chat panel that only returns code suggestions, Cline reads your project files, edits them directly, runs terminal commands, and iterates on the result, asking for your approval at every step (docs.cline.bot, fetched 2026-10-30). It runs on what its makers call one open agent runtime, trusted by more than 11 million developers (cline.bot, fetched 2026-10-30).
If you already use an agent-style coding tool, this Claude Cowork beginner guide shows the agent-task lane; Cline is the in-editor lane, with the plan-first loop that makes it different from autocomplete tools. You give it a goal like "add a --json flag to this script," and it plans the steps, shows you the diff for each change, runs the command, and fixes what breaks — a pair-programming partner with strict boundaries.
What do you need before installing Cline?
You need VS Code (the classic home of Cline) — though the same experience now also ships for Cursor, Windsurf, JetBrains IDEs, Antigravity, Zed, and Neovim via ACP mode, plus a standalone desktop app and a terminal CLI (docs.cline.bot, fetched 2026-10-30). The second thing you need is a model for the agent to think with. Cline offers three access paths: Cline usage-billing (one sign-in, built-in billing, free model options), ClinePass at a flat $9.99/month (advertised as 2–5x the usage on popular open coding models compared to standard API rates), or Bring Your Own Key with your own provider credentials (docs.cline.bot, fetched 2026-10-30).
BYOK is the path most beginners start with: paste an API key from Anthropic, OpenAI, or OpenRouter, or point Cline at a local Ollama endpoint. OpenRouter is handy if you want to compare Claude, GPT, and other models through a single key, and a local model costs nothing per token — this Ollama beginner guide covers the local-model branch. Two cost warnings from a hands-on walkthrough apply from day one: Cline can burn through tokens quickly because it reads files and runs commands in a loop, and a cheap model is enough to learn the workflow before you switch to a capable one for real work (Enterprise DNA, enterprisedna.co, fetched 2026-10-30).
How do I install Cline in VS Code?
Installation takes a few minutes and looks like this:
- Open the Extensions view with Ctrl+Shift+X (Cmd+Shift+X on Mac) and search for "Cline" — check the publisher reads saoudrizwan before you install, since you are about to grant an extension shell access (Enterprise DNA, enterprisedna.co, fetched 2026-10-30).
- Click Install, then click the new Cline icon in the Activity Bar to open its panel. It looks like a chat window — that panel is the whole product.
- Pick a provider in the API configuration: Anthropic, OpenAI, OpenRouter, a local Ollama endpoint, Cline usage-billing, or ClinePass.
- Enter your API key for the provider you chose. For Anthropic and OpenAI, Cline stores the key in VS Code's secret storage rather than plain text (Enterprise DNA, enterprisedna.co, fetched 2026-10-30).
- Choose a model that fits your task and budget — small and cheap while you learn, capable when you do real work. Switching models mid-session is a one-click change.
The first time Cline asks to run a terminal command, VS Code may ask you to confirm that you trust the workspace for shell execution — a one-time prompt (Enterprise DNA, enterprisedna.co, fetched 2026-10-30). Once you are set up, the real learning begins with your first task.
How do Plan mode and Act mode work?
Plan and Act are the two modes Cline uses for every job, and understanding the split is the fastest way to stop fighting the agent. Plan mode explores first: the agent reads your directory structure, inspects dependencies, and formulates an implementation strategy. Act mode executes: it makes the multi-file edits, runs the terminal commands, and validates the result in real time. Nothing in either mode happens silently — every action requires your explicit approval, and you are always in control (docs.cline.bot, fetched 2026-10-30).
| Mode | What the agent does | What you do |
|---|---|---|
| Plan mode | Explores the codebase, reads docs, proposes an implementation strategy | Read the plan, correct the approach before a single file is touched |
| Act mode | Applies the edits with linter-aware fixes, runs tests and commands | Approve each diff and command; undo any step with one click |
The habit to build: never skip Plan mode on anything larger than a typo fix. A two-minute correction to a plan costs nothing; a two-hour correction to executed code costs an afternoon. When the strategy looks right, flip to Act and watch it execute.
How do I give Cline my first task?
Start with a task you can describe in two sentences. The narrower the task, the better Cline performs — "add input validation to the signup form" beats "improve the auth system" every time (Enterprise DNA, enterprisedna.co, fetched 2026-10-30). Here is an original first-task recipe you can run in a fresh empty folder:
- Open a new empty folder in VS Code and open the Cline panel.
- Type a scoped goal: "Create a Python script called status_check.py that takes a list of URLs and prints each one's HTTP status code. Then run it against three example URLs and show me the output."
- Read the plan. Cline responds with the steps it intends to take — create the file, run the script. Correct the approach now if anything looks off.
- Approve the file creation when the diff looks right, then approve the terminal command when you are happy with what it will run.
- Watch the loop. Cline writes the file, runs the script, reads the output, and reports back. If the script fails because a library is missing, it installs it and retries; if something is genuinely ambiguous, it asks you how to proceed instead of guessing (this acting-in-your-environment loop is what separates an agent from a chatbot, per the Enterprise DNA walkthrough, fetched 2026-10-30).
- Give a follow-up turn to feel the real product: "add a timeout of five seconds to every request and retry each URL once." Cline reads the existing file, plans the edit, shows the diff, and applies it.
That back-and-forth — small well-defined task, review the diff, iterate — is the actual workflow. The first prompt is just the entry point.
What are Cline rules, and how do I set them?
Cline rules are project instructions that get injected into every request, so the agent follows your conventions without being reminded. The official mechanism is the .clinerules file: ship it in your repo root to teach the agent your coding standards, architecture, and deployment conventions (cline.bot, fetched 2026-10-30).
Keep your rules short and specific — a paragraph beats a page, because long instruction blocks get ignored as the context window fills up (Enterprise DNA, enterprisedna.co, fetched 2026-10-30). Rules that tend to stick: "always run the test suite before claiming a task is done," "never edit files outside the src folder," "never modify generated files." A shared .clinerules file checked into version control also keeps every engineer's Cline behaving the same way on team projects.
The approve-every-diff rule: how do you stay in control?
By default, Cline asks you to approve every file write and every terminal command — that confirmation prompt is the product's core safety line, and every action requires your explicit approval (docs.cline.bot, fetched 2026-10-30). Approve every diff the way you would approve a teammate's pull request: read what changed, then click. There is an auto-approve toggle for when you are ready to loosen things up, and the smart way to use it is per-category rules — "always allow file reads but always ask for terminal commands" — rather than blanket autopilot (Enterprise DNA, enterprisedna.co, fetched 2026-10-30).
For a sandbox project, auto-approve is fine. For your real codebase, keep the prompts on until you trust the workflow, then loosen them selectively. Also consider a dedicated branch or throwaway folder for agent-driven changes: let Cline work freely there, review the diff at the end, and merge what survived review — your main branch stays clean and you get a clean rollback path (Enterprise DNA, enterprisedna.co, fetched 2026-10-30).
Which model should I use with Cline?
Cline is the harness, not the brain — a weak model produces weak results, so picking a model that matches the task is part of using it well (Enterprise DNA, enterprisedna.co, fetched 2026-10-30). Use this ladder:
| Job | Pick | Why |
|---|---|---|
| Learning the workflow | Small, cheap model (e.g. Claude Haiku-class or GPT-4o-mini-class) | Enough to learn the planning loop; keeps the bill low while you experiment |
| Multi-step real work | Larger capable model (e.g. Claude Sonnet-class) | Better planning and fewer mistakes on complex tasks, slower and pricier |
| Comparing models | OpenRouter with BYOK | One key reaches models from many vendors |
| Zero per-token spend | Local model via Ollama or LM Studio | Free per token, but you need a machine that can actually run the model |
| Simplest start | Cline usage-billing | One sign-in, built-in billing, free model options — no API keys to manage |
Track the cost as a habit: the loop is so smooth that it is easy to spend more on API calls than you intended. Set a budget, watch the token counter, and use cheaper models for routine tasks (Enterprise DNA, enterprisedna.co, fetched 2026-10-30). If you chose a Claude model, this Claude beginner guide covers the model family itself.
What is MCP, and what does it unlock in Cline?
MCP — the Model Context Protocol — is the standard Cline uses to plug the agent into your tools and data. Through it you can register custom tools and lifecycle hooks, and connect MCP servers for databases, APIs, and infrastructure (cline.bot, fetched 2026-10-30). In practice that means Cline can reach beyond files and the terminal: query your database before writing the migration, check the CI status before claiming a task is done, or pull live API docs while writing an integration. Cline also ships a browser tool, so it can open pages and read what is actually there. Set up MCP servers for the systems you touch daily, and the agent stops being a smart editor and starts being a connected teammate.
Should I use Cline or Cursor?
They solve the same problem with different philosophies. Cline is an open-source extension (and now desktop app, CLI, and SDK) that works inside editors you already have — VS Code, Cursor, Windsurf, JetBrains, Zed, Neovim via ACP — and pairs with any model through BYOK, Cline billing, or ClinePass (docs.cline.bot, fetched 2026-10-30). Cursor is a full editor of its own with the AI woven in, which some beginners find more turnkey. If you like your current editor and want model freedom with an inspectable open-source harness, Cline is the natural pick; if you want one download that decides everything for you, try Cursor. Either way, the sibling comparison with the other big assistant lane is in this GitHub Copilot beginner guide.
What mistakes do Cline beginners make?
Four mistakes show up again and again in real-world use (all documented in the Enterprise DNA walkthrough, fetched 2026-10-30). Long sessions lose context: after enough back-and-forth the history gets trimmed and Cline forgets earlier agreements — for multi-hour work, summarize the state yourself or restart with a fresh prompt. Hallucinated APIs: on less common libraries it sometimes invents methods that don't exist — keep dependencies pinned and actually run the code it produces. Surprise bills: track tokens and set a budget; the loop's smoothness is exactly what makes overspending easy. Auto-approve on the real codebase: terminal commands and deletions deserve a human eye — treat Cline's output as a draft, not a final answer, and remember that no agent replaces code review.
Sources
- Cline official site, cline.bot — fetched 2026-10-30: the open agent, 11M+ developers, Desktop/IDE/CLI/SDK/Kanban surfaces, Plan-and-Act, every-model choice, Rules and Skills, MCP and plugins.
- Cline docs, docs.cline.bot — fetched 2026-10-30: "every action requires your explicit approval"; model access (Cline usage-billing with free model options, ClinePass $9.99/month with 2–5x usage on popular open coding models vs standard API rates, Bring Your Own Key); editor support (VS Code, Cursor, Windsurf, JetBrains, Antigravity, Zed, Neovim via ACP); CLI
npm i -g cline, SDKnpm install @cline/sdk, Kanbannpx kanban. - Enterprise DNA, "Cline VSCode Tutorial: Setting Up an AI Coding Agent" — fetched 2026-10-30: install via VS Code Marketplace (publisher saoudrizwan), provider picker, API key stored in VS Code secret storage, approval modes, custom instructions, token-cost caution, limitations (context loss, hallucinated APIs, large codebases, no TTY, still needs code review).
- Sider.ai, "How to Use Cline: A Practical Guide to the AI Coding Agent in VS Code" — crawled 2026-10-29: install steps, model provider choice, safety and workspace boundaries, quick-start workflow.
- AI Sharing Circle, "Cline (Claude Dev): a VSCode plugin for automated programming" — fetched 2026-10-30: the project's history as Claude Dev, permission-before-each-step design.
Frequently Asked Questions
Is Cline free to use?
Cline itself is open source. For model access you choose: Cline usage-billing with free model options, ClinePass at a flat $9.99/month, or Bring Your Own Key where the cost is your own provider's API bill — local models via Ollama cost nothing per token (docs.cline.bot, fetched 2026-10-30). The extension charges you nothing; the intelligence is what you pay for.
What models work with Cline?
Claude, GPT, Gemini, local Ollama or LM Studio models, or any OpenAI-compatible endpoint — you can bring your own key or your own weights (cline.bot, fetched 2026-10-30). OpenRouter through one key lets you compare models from many vendors without juggling accounts.
What is the difference between Plan mode and Act mode?
Plan mode explores: Cline reads your codebase and proposes an implementation strategy. Act mode executes: it applies the edits, runs terminal commands, and validates the result. You approve the plan before anything is touched, then approve each diff and command as it executes.
How is Cline different from GitHub Copilot?
Copilot is primarily an autocomplete and chat assistant inside your editor, while Cline is an agent: it plans multi-step tasks, edits files, runs terminal commands, and iterates on failures with your approval at each step. Cline is open source and model-agnostic; you can even run Cline inside VS Code while comparing it against Copilot's lane.
Does Cline work with editors other than VS Code?
Yes. Beyond VS Code, Cline supports Cursor, Windsurf, JetBrains IDEs (IntelliJ, PyCharm, WebStorm and others), Antigravity, and Zed, plus Neovim via ACP mode — and there is a standalone Cline Desktop app and a terminal CLI for editor-free use (docs.cline.bot, fetched 2026-10-30).