How to Use Cline: AI Coding Assistant Guide (2026)

How to Use Cline: AI Coding Assistant Guide (2026)

Cline is an open-source AI coding assistant that runs inside VS Code and gives you an autonomous agent capable of creating files, editing code, running terminal commands, and even browsing the web. Unlike simple autocomplete tools, Cline operates as a full agentic coding partner that can execute multi-step tasks across your entire codebase.

This guide covers everything from installation to advanced workflows so you can get productive with Cline immediately.

What Is Cline?

Cline (formerly known as Claude Dev) is a VS Code extension that connects to various LLM providers and uses tool-calling to interact with your development environment. It can read and write files, execute shell commands, search your codebase, and use the browser -- all while asking for your approval at each step.

Key Features

Feature	Description
Multi-file editing	Create, edit, and delete files across your project
Terminal execution	Run commands and interpret output
Browser integration	Navigate web pages to read docs or test UIs
MCP support	Connect to external tools via Model Context Protocol
Multi-provider	Works with Anthropic, OpenAI, Google, OpenRouter, local models
Approval workflow	Review and approve each action before it executes
Context mentions	Use @file, @folder, @url to add context

Step 1: Install Cline in VS Code

Open VS Code and install the extension:

1. Press Ctrl+Shift+X (or Cmd+Shift+X on macOS) to open the Extensions panel.
2. Search for "Cline".
3. Click Install on the extension by saoudrizwan.

Alternatively, install from the terminal:

code --install-extension saoudrizwan.claude-dev

After installation, you will see a Cline icon in the VS Code activity bar (left sidebar).

Step 2: Configure Your API Provider

Click the Cline icon in the sidebar to open the panel. You need to configure an API provider before you can start.

Option A: Anthropic API (Recommended)

Provider: Anthropic
API Key: sk-ant-xxxxxxxxxxxxx
Model: claude-sonnet-4-20250514

Option B: OpenRouter (Access Multiple Models)

Provider: OpenRouter
API Key: sk-or-xxxxxxxxxxxxx
Model: anthropic/claude-sonnet-4

Option C: Local Models via Ollama

Provider: Ollama
Base URL: http://localhost:11434
Model: deepseek-coder-v2

Provider Comparison

Provider	Best For	Cost	Latency
Anthropic (Claude)	Best overall coding quality	$$$	Low
OpenRouter	Model variety, cost flexibility	$-$$$	Low-Medium
Google (Gemini)	Large context windows	$$	Low
Ollama (Local)	Privacy, offline use, free	Free	Varies
OpenAI	GPT-4o for broad tasks	$$$	Low

Step 3: Your First Task

With the API configured, type a task in the Cline input box at the bottom of the panel. Start with something simple:

Create a new Express.js server in src/server.ts with a health check endpoint at /api/health that returns { status: "ok" }.

Cline will:

1. Plan the approach and show you the steps.
2. Create the file src/server.ts with the code.
3. Ask for your approval before writing.
4. Optionally run npm install express if needed.

You approve or reject each step. This human-in-the-loop approach prevents unwanted changes.

Step 4: Use Context Mentions

Cline supports @ mentions to add context to your prompts:

Look at @src/lib/auth.ts and @src/lib/database.ts and create a new
endpoint that authenticates users and stores session data.

Available context mentions:

Mention	What It Does
@file	Includes a specific file's contents
@folder	Includes a directory listing
@url	Fetches and includes a web page
@problems	Includes VS Code diagnostics/errors
@terminal	Includes recent terminal output

Step 5: Configure Custom Instructions

You can add custom instructions that persist across all conversations. Go to the Cline settings and add instructions like:

Always use TypeScript with strict mode.
Use functional components with React hooks.
Prefer Tailwind CSS for styling.
Write tests using Vitest for all new functions.
Follow the project's existing code patterns.

These instructions are prepended to every message, ensuring consistent code style.

Step 6: Set Up MCP Servers

Cline supports the Model Context Protocol (MCP), which lets you connect external tools. Configure MCP servers in the Cline settings panel under "MCP Servers."

Example: Adding a GitHub MCP server:

{
  "github": {
    "command": "npx",
    "args": ["-y", "@modelcontextprotocol/server-github"],
    "env": {
      "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_xxxxxxxxxxxx"
    }
  }
}

With GitHub MCP connected, you can ask Cline to:

• Create issues and pull requests
• Read PR reviews and comments
• Search repository code
• Manage branches

Step 7: Use the Browser Tool

Cline can launch a browser to navigate web pages, click elements, fill forms, and take screenshots. This is useful for:

• Reading documentation from URLs
• Testing your web application
• Scraping information for your task

Go to https://docs.stripe.com/api/charges and summarize the
required parameters for creating a charge. Then create a
TypeScript function that wraps this API.

Cline will open a headless browser, read the page, and use the information to generate code.

Step 8: Manage Costs with Auto-Approve Settings

By default, Cline asks for approval on every action. You can auto-approve certain actions to speed up workflows:

Setting	Description
Auto-approve reads	Automatically approve file reads
Auto-approve writes	Automatically approve file writes (use cautiously)
Auto-approve commands	Automatically approve terminal commands
Auto-approve browser	Automatically approve browser actions

For most developers, auto-approving reads is safe and speeds up the workflow significantly. Be more cautious with write and command approvals.

Practical Workflows

Debugging a Production Error

I'm getting this error in production:

TypeError: Cannot read properties of undefined (reading 'map')
at UserList (src/components/UserList.tsx:23:18)

Look at the component, find the bug, fix it, and add a null check
to prevent this from happening again.

Refactoring a Module

Refactor @src/utils/helpers.ts to:
1. Split into separate files by concern (string, date, validation)
2. Add TypeScript types to all functions
3. Add JSDoc comments
4. Update all imports across the project

Adding a Feature End-to-End

Add a user profile page with the following:
1. A new route at /profile
2. A React component that displays user info
3. An API endpoint at /api/user/profile
4. Database query to fetch user data
5. Unit tests for the API endpoint

Cline vs. Other AI Coding Tools

Feature	Cline	GitHub Copilot	Cursor	Claude Code (CLI)
Multi-file editing	Yes	Limited	Yes	Yes
Terminal commands	Yes	No	Yes	Yes
Browser automation	Yes	No	No	No
MCP support	Yes	No	Yes	Yes
Open source	Yes	No	No	No
Model flexibility	Any provider	GPT-4o/Claude	Multiple	Claude only
Interface	VS Code panel	VS Code inline	Custom editor	Terminal
Human-in-the-loop	Yes (per action)	Auto	Mixed	Yes

Troubleshooting

Cline is not responding after sending a task: Check that your API key is valid and the selected model is available. Open the VS Code output panel (View > Output) and select "Cline" from the dropdown to see error logs.

High API costs: Use a cheaper model for simple tasks. DeepSeek or Claude Haiku are significantly cheaper than Claude Opus for routine coding. You can also use local models via Ollama for free.

File edits are incorrect or incomplete: Provide more context with @file mentions. The more context Cline has about your project structure and patterns, the better the output.

Browser tool not working: Make sure you have Chrome or Chromium installed. The browser tool requires a Chromium-based browser to function.

Wrapping Up

Cline is one of the most capable open-source AI coding assistants available in 2026. Its combination of multi-file editing, terminal access, browser automation, and MCP support makes it a genuine agentic coding partner rather than just an autocomplete tool. The human-in-the-loop approval system gives you control while still enabling fast, autonomous workflows.

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