How to Set Up an AI Coding Assistant

Setup takes about 15 minutes for one developer. Most of the value comes from steps 4 and 5, which people often skip.

1. Pick a tool that fits how you already work

The best assistant is the one that runs where you spend your day. Changing editors to try a tool adds friction you’ll blame on the AI.

• You use VS Code or a JetBrains IDE: start with an extension, such as GitHub Copilot, Claude Code, Codex or Cline.
• You work in the terminal: Claude Code, the Codex CLI, Aider and the Copilot CLI all run there.
• Your company already pays for a platform: check whether GitHub, Google Cloud or AWS licensing already covers Copilot, Antigravity, Amazon Q Developer or Kiro. That also settles most security questions in advance.

The AI coding assistant comparison lists where each tool runs, what’s free and what the first paid plan costs.

2. Install it

Use the vendor’s official install instructions and nothing else. Typosquatted extensions and look-alike packages are a real risk with popular developer tools.

Examples from the official documentation:

Editor extensions install from the VS Code Marketplace or JetBrains Marketplace. Check that the publisher is the vendor before you click Install.

After installing a command-line tool, open a new terminal and run its version command, for example claude --version. If the command isn’t found, the install directory isn’t on your PATH yet.

3. Sign in with the right account

Sign in with the account your work is covered by, not whichever one the browser offers first. Most tools open a browser window to log in. If you have both a personal and a work account, use a private browser window so you pick the right one.

Many tools also accept an API key instead of a subscription. That suits automation and CI, but you pay per use, so set a spending limit in the provider’s console first.

4. Set permissions and data settings before your first real task

Decide what the assistant may do on its own before it does anything. Coding agents can edit files and run shell commands, which is what makes them useful and what makes them risky.

• Commands: keep “ask before running commands” on at first. Allow specific safe commands, such as your test runner, once you trust the workflow.
• Files: run the tool from the project folder, not from your home directory, so it only sees that project.
• Secrets: keep .env files and credentials out of the project folder, or tell the tool to ignore them. Never paste production secrets into a chat.
• Data use: read the tool’s privacy settings and your plan’s terms on whether your code may be used for training. Business plans often differ from individual ones.

These settings matter because of prompt injection: text in a file, issue or web page can contain instructions aimed at the AI. Limiting what the agent can do limits the damage.

5. Add a project rules file

A short rules file is the highest-value 10 minutes in the whole setup. It tells the assistant how to build, test and style code in this project, so you don’t repeat it in every prompt.

Create AGENTS.md in the repository root (or the file your tool expects, such as CLAUDE.md or .github/copilot-instructions.md) with:

• how to install dependencies, build and run the tests
• the main folders and what lives in them
• coding conventions that differ from the language defaults
• things the assistant must never do, such as editing generated files or committing to main

See How to write project rules for AI coding assistants for a full template.

6. Start with a small task you can fully review

Your first task should be small, real and easy to verify. Good first tasks:

• write unit tests for an existing, well-understood function
• explain an unfamiliar module and draw its call flow
• fix a small, reproducible bug that already has a failing test
• update a dependency and fix the resulting deprecation warnings

Read every line of the result, run the tests and check the diff before committing. Then follow How to review AI-written code to build the habit.

Common setup problems

• “Command not found” after install: open a new terminal; if that doesn’t help, add the install directory to your PATH.
• The assistant ignores your conventions: check that the rules file has the exact name and location your tool expects, and keep it short.
• Results are vague or wrong: give it the specific files, the exact error message and the expected behavior. Vague prompts get vague code.