How to Use Cline

Cline (formerly Claude Dev) is an autonomous coding agent that lives in a VS Code side panel. It reads your files, edits them, runs terminal commands, and can drive a browser — all with a human-in-the-loop approval gate so you see every diff before it lands.

What Cline actually is

Cline is a VS Code extension that wraps a frontier LLM in a tool-using agent loop. Each turn it picks one tool — read file, write file, run command, search, fetch URL, use a browser — and you approve or reject the action. The model you bring supplies the intelligence; Cline supplies the plumbing, a diff UI, and the permission prompts.

Installing

Install the Cline extension from the VS Code Marketplace (the publisher is saoudrizwan). Open the side panel, pick a provider — Anthropic, OpenRouter, AWS Bedrock, GCP Vertex, or a local Ollama endpoint — and paste a key. OpenRouter is the easy button if you want to try Claude, GPT, and Gemini without three separate accounts.

A first task

Open the Cline panel, type something concrete: “add a /api/users/:id route with zod input validation, a happy-path test, and update the OpenAPI file.” Cline will plan, list files, open the ones it needs, and propose edits in a diff view. Hit approve for each step, or toggle Auto-approve for read-only actions so it does not pause on every cat.

Plan vs Act mode

Plan mode is chat-only — the agent can read but not write. Use it to negotiate the design first (“where should this live, which existing helper do we reuse”) and then switch to Act to execute. Skipping Plan on anything non-trivial is the most common way Cline users burn tokens on a first draft they have to throw away.

Configuration that matters

Set Auto-approve for reads and shell commands you trust (lint, test, typecheck), but keep rm, git push, and writes outside the workspace gated. Add a .clinerules file — it is injected into the system prompt, and it is how you tell Cline “always use pnpm, never npm” or “run our make check before claiming done.” Cap context window spend via the model selector if you are using Sonnet on a long session.

When Cline shines

Medium-to-large features where you want an agent that can run the test suite, read the failure, and keep iterating — all while you review diffs visually in VS Code. The browser tool is genuinely useful for checking a running frontend without tab-switching.

When not to use it

If you live in JetBrains or Neovim, Cline is not for you — try Continue or Aider instead. It is also overkill for single-line tweaks where Copilot-style inline completion is faster. And watch the bill: running Claude Sonnet on a repo with a big context can cost more in one afternoon than a month of Copilot, so set a provider spend limit on day one.