What Is Cline AI? Install It in VS Code, Connect an API, and Work Safely

Cline—also searched as Cline AI, ClineAI, or Cline agent—is an open-source AI coding agent that works in your editor and terminal. Inside VS Code, it can read project files, search code, edit files, run terminal commands, use a browser, and call MCP tools, while asking for approval according to your permission settings. Cline itself is not a language model. It connects to a model provider and uses the selected model for reasoning and code generation.

This guide explains what Cline is, how to install it in VS Code, how to connect your own API through the OpenAI Compatible provider, and how to verify the setup without giving the agent unnecessary access. BetterToken is used for the configuration example, but the underlying workflow also applies to other compatible endpoints.

The essentials

• Cline is a coding agent, not a model.
• After installing the VS Code extension, you can use Cline’s built-in model access or bring your own API key.
• For BetterToken, select OpenAI Compatible and use https://www.bettertoken.ai/v1 as the Base URL.
• Start with read-only access. Do not enable automatic edits, terminal commands, browser access, MCP, or YOLO Mode on the first task.

What Cline, VS Code, and the model API each do

A typical Cline task has three layers:

1. VS Code displays the project, conversation, diffs, terminal output, and approval prompts.
2. The Cline agent gathers context, chooses tools, organizes the task, and checks your permission settings.
3. The model API receives the context and returns analysis, code, or a suggested tool call.

The result therefore depends on more than the extension. The model affects reasoning quality, coding ability, speed, context size, and cost. Cline settings determine which files and tools the model can use and which actions require your approval.

That is the main difference between Cline and a basic chat extension. A chat extension usually produces text. Cline works in an agent loop: read information, propose the next step, call a tool, inspect the result, and continue until the task is complete or a decision is needed.

How to install Cline in VS Code

1. Open VS Code.
2. Press Ctrl/Cmd + Shift + X to open Extensions.
3. Search for Cline and choose the official Cline extension.
4. Click Install.
5. Open Cline from the Activity Bar.
6. On the onboarding screen, choose Use your own API key to configure a custom provider.

If the icon does not appear after installation, run Developer: Reload Window or fully restart VS Code. Labels may change slightly between releases, but the provider and model settings remain available from the Cline sidebar.

What you need before connecting an API

To connect Cline to BetterToken, prepare:

• a BetterToken account;
• a dedicated API key;
• a current Model ID copied from the models and pricing page;
• a network connection that can reach the model endpoint;
• current versions of VS Code and the Cline extension.

Treat the API key like a password. Do not commit it to a repository or expose it in screenshots, logs, issues, or public configuration files. For teams, separate keys by user or environment so that limits, revocation, and request tracing remain manageable.

Configure the BetterToken API in Cline

Open Cline settings and enter the following provider values:

Field	Value
API Provider	OpenAI Compatible
Base URL	https://www.bettertoken.ai/v1
API Key	Your BetterToken API key
Model	The exact current Model ID from the model page

Keep these details in mind:

1. Use https://www.bettertoken.ai/v1 as the Base URL. Do not append /chat/completions, /responses, or another request path.
2. Copy the Model ID exactly from the current model page instead of an old article or screenshot.
3. Extra User-Agent or custom headers are normally unnecessary. Add them only when official upstream documentation explicitly requires them.
4. Not every model necessarily uses the same protocol. Check the currently verified compatibility in the BetterToken Cline setup documentation.

If you previously configured OpenAI environment variables and Cline keeps using an old endpoint, clear them in the current macOS or Linux shell:

unset OPENAI_API_KEY
unset OPENAI_BASE_URL

In Windows PowerShell:

Remove-Item Env:OPENAI_API_KEY -ErrorAction SilentlyContinue
Remove-Item Env:OPENAI_BASE_URL -ErrorAction SilentlyContinue

Save the settings with Done, then reload Cline. After changing the Base URL, API key, or Model, start a new task so an old session does not retain stale configuration or an oversized context.

Run a read-only test first

Do not make “refactor the entire project” your first request. Open a normal code file and send this prompt:

Read only the currently open file. Explain its purpose, main inputs, and outputs. Do not modify any files and do not run terminal commands.

A successful first test should meet four conditions:

• Cline returns an explanation grounded in the file;
• no authentication, model, or connection error appears;
• no file is edited and no command is executed;
• the request and token usage appear in the BetterToken Dashboard.

If Cline responds but no request appears in the Dashboard, verify that the active provider is really OpenAI Compatible, then check the Base URL, API key, Model ID, and network proxy. Never share the full key in a public screenshot while asking for help.

How a Cline coding task works

A typical task follows this cycle:

1. You define the desired result, allowed scope, and completion criteria.
2. Cline reads relevant files and searches for related code.
3. The model proposes the next step: read more, edit a file, run a test, or ask a question.
4. Cline checks the permission category and asks for approval when required.
5. Tool output is added to the context, and the model decides what to do next.
6. You review the final diff, command output, and test results.

For unclear work, start in Plan Mode. Cline can inspect and discuss the codebase there, but it does not edit files or execute commands. Once the approach is agreed, switch to Act Mode and let it implement the plan.

For example, start in Plan Mode with:

Investigate why the login endpoint sometimes returns HTTP 500. Read only the relevant code and tests. List the most likely root causes, affected files, and the smallest safe fix. Do not change code.

After reviewing the plan, switch to Act Mode:

Apply the smallest approved fix. Modify only the login endpoint and directly related tests. Run the most relevant tests and stop when they pass. Do not refactor unrelated modules.

This is much easier to verify than a vague request such as “fix login.”

Recommended permissions for your first tasks

Start with a conservative profile:

Permission	Initial recommendation
Read project files	On
Read all files / outside the workspace	Off
Edit project files	Ask every time, or keep off initially
Execute safe commands	Approve manually for the first tasks
Execute all commands	Off
Use the browser	Enable only for a specific need
Use MCP servers	Enable only after validating a specific server
YOLO Mode	Keep off for real projects

When approving a command, inspect the arguments, working directory, and target files—not just the command name. npm test and npm install have different consequences; so do git status and git push.

Checkpoints and Git can help you undo local code edits, but they cannot reverse an external network request, restore deleted cloud data, or unexpose a leaked secret. Use a branch or worktree for important repositories and keep sensitive files outside the agent’s access whenever possible.

API, MCP, and Cline Rules solve different problems

These concepts are often mixed together:

• The model API provides the reasoning and generation capability.
• MCP gives Cline external tools and data sources, such as databases, hosted services, or internal systems.
• Cline Rules describe project conventions, architectural constraints, testing expectations, and working practices.

MCP does not replace the model API. A reliable order is: connect the API and pass a read-only test, add project rules, then connect only trusted MCP servers required for a specific workflow. Store MCP credentials in environment variables or a secure secret store rather than committing them to the repository.

How Cline pricing works

Cline is open source, but model execution still consumes compute. Cline offers several model-access paths, including built-in usage billing, subscriptions, and bring-your-own-key. BetterToken is a BYOK-style setup, so the final charge comes from the model requests you make.

Usage may include:

• input tokens: prompts, project files, rules, and task history;
• output tokens: responses, generated code, and tool-call content;
• cache tokens: only when the selected model and endpoint support caching.

The cost displayed inside Cline is generally an estimate. Use the provider bill or BetterToken Dashboard as the final record. To reduce wasted context and cost:

• give each task one verifiable objective;
• avoid loading the entire repository without a reason;
• search and read before asking for broad changes;
• start a new task when the topic changes;
• check current model pricing before a long run;
• use a faster, cheaper model for straightforward work when its tool use is reliable;
• plan before acting on larger changes to avoid repeated rework.

Common errors and how to fix them

Symptom	Check first
401, Unauthorized, or Invalid API Key	Key accuracy, leading/trailing spaces, and whether the key was revoked
404	Base URL must be exactly https://www.bettertoken.ai/v1; remove endpoint suffixes
model not found	Copy the current Model ID exactly, including case and punctuation
Old settings remain active	Save, reload the extension or restart VS Code, and create a new task
Connection keeps failing	Local network, proxy, firewall, and DNS access to the endpoint
Cline responds but Dashboard is empty	Active provider, account, stale environment variables, and Base URL
Strange output or failed tool calls	Whether the model is suitable for agent/tool use and whether model fields are accurate
Token usage grows too quickly	Oversized context, long task history, or repeated reads of the same files

Change one variable at a time. Confirm Provider, Base URL, key, and Model before tuning advanced fields such as context size, output limits, headers, or proxy behavior.

Tasks that fit Cline well

Cline is useful for:

• understanding an unfamiliar module and locating related files;
• fixing a bounded bug with reproduction steps or an existing test;
• applying a consistent change across several files;
• running lint, build, or tests and explaining failures;
• implementing a clearly scoped feature using existing project patterns;
• calling MCP tools under an explicit access policy.

Here is a practical task prompt:

Goal: add status filtering to the order list.
Allowed scope: the order-list page, directly used query parameters, and related tests.
Do not: refactor the order module, upgrade dependencies, or change payment logic.
Completion criteria: users can select a status and see correct results; the filter remains after a page refresh.
Verification: run the order-list tests and stop when they pass.

Cline may be unnecessary for a one-line question. It should not receive unrestricted access to a highly sensitive repository without isolation and policy controls. For fixed, repeated, unattended workflows, the CLI or a CI integration may be a better fit than keeping VS Code open.

Frequently asked questions

What is Cline AI?

Cline is an open-source AI coding agent for editors and terminals. It can read code, edit files, run commands, use a browser, and call MCP tools. An external model API provides reasoning and generation, while Cline’s permission system keeps tool use under user control.

Are ClineAI, Cline agent, and Cline the same thing?

In search queries, these terms usually refer to the same coding agent. The official product name is Cline.

Does Cline work in VS Code?

Yes. The official extension runs in the VS Code sidebar and shows the conversation, diffs, task status, and approval requests.

How do I connect my own API to Cline?

Choose the appropriate provider in Cline settings. For BetterToken, select OpenAI Compatible, enter https://www.bettertoken.ai/v1, your BetterToken API key, and an exact current Model ID, then save and reload the extension.

Do I need a Cline subscription?

Not necessarily. Cline supports multiple model-access options, including its own billing paths and bring-your-own-key. The best choice depends on your account, region, models, and budget.

What is the difference between Cline and MCP?

Cline is the agent that carries out coding tasks. The model API supplies intelligence. MCP adds external tools and data. They are complementary layers, not alternatives.

Is Cline safe?

Safety depends on permissions, prompts, the selected model, MCP servers, and the project environment. Minimum access, command review, version control, secret isolation, and keeping YOLO Mode off by default substantially reduce risk.

Conclusion

Cline is more than a chat box in VS Code. It brings project context, file changes, terminal commands, and reviewable diffs into one agent workflow. The right way to start is to install the official extension, configure one model API, pass a read-only test, and then expand edit, command, browser, and MCP permissions only when needed.

With BetterToken, use OpenAI Compatible, the Base URL https://www.bettertoken.ai/v1, your own API key, and a current valid Model ID. Begin with a small, specific task and treat every new permission as a deliberate decision.

Further reading:

• Cline official overview
• Cline installation guide
• Cline OpenAI-compatible provider setup
• BetterToken Cline setup guide
• Create a BetterToken account