Your coding agents are capable of so much more—they just need an operating system. Introducing, Agent OS.
Agent OS transforms AI coding agents from confused interns into productive developers. With structured workflows that capture your standards, your stack, and the unique details of your codebase, Agent OS gives your agents the specs they need to ship quality code on the first try—not the fifth.
Stop wrestling with AI that writes the wrong code. Agent OS transforms coding agents from confused assistants into trusted developers who truly understand your codebase.
3 reasons why product teams use Agent OS:
Unlike basic AI setups, Agent OS provides three layers of context that work together:
The result: Agents write code that looks like you wrote it—first time, every time.
Agent OS replaces random prompting and circular rewrites with a proven workflow. It automatically:
The difference: Ship features faster with clear specs and completed tasks—not endless cycles of (re)explaining requirements and redoing work.
Agent OS is completely yours to shape. Define your own coding standards, write custom instructions, and adapt every workflow to match how your team operates. No rigid interfaces or prescribed processes—just markdown files you control. Works seamlessly with any AI tool or IDE you choose.
The relief: Your coding agent finally feels like a senior developer on your team—thinking your way, following your patterns, and shipping at your standards.
Agent OS works by layering context—just like you'd onboard a human developer. Each layer builds on the previous one, creating a complete picture of how you build software.
Your standards define how you build software. Your stack. Your opinions. Your style. Your priorities. The standards you expect everyone on your team to follow when building anything. These should include:
Your standards documentation lives on your system in ~/.agent-os/standards/...
and are referenced from every project, every codebase. Set once, use everywhere, override as needed.
At the product (codebase) layer, we document what it is we're building, why we're building it, who it's for, and the big-picture product roadmap. This includes:
Product documentation lives in your codebase (.agent-os/product/
) and give agents the full picture of your product.
Throughout your product's development, you'll create many specs. Each spec is a single feature or enhancement or fix, which typically represents a few hours or days of work (accellerated with the help of AI). Each spec will have its own requirements, technical specs, and tasks breakdown.
Individual feature specifications include:
Specs live in dated folders inside your codebase (.agent-os/projects/2025-12-19-user-auth/
) and guide agents through each spec's implementations.
With all three layers in place, your agent has everything it needs: how you build (Standards), what you're building (Product), and what to build next (Specs). No more confusion, no more rewrites—just clean, consistent code that looks like you wrote it.
Getting started with Agent OS is a two-step process:
Installing Agent OS in an existing codebase that's been around a while? Then see Working with Existing Codebases.
See What Gets Installed Where? to understand where all the Agent OS files will live after installation.
Everyone starts here. The fastest way to get started is by running the install script with this one-liner in your terminal:
curl -sSL https://raw.githubusercontent.com/buildermethods/agent-os/main/setup.sh | bash
~/.agent-os/
folder in your home directory.--overwrite-instructions
to update and overwrite instruction files when needed.--overwrite-standards
to update and overwrite standards files when needed.mkdir -p ~/.agent-os/standards
mkdir -p ~/.agent-os/instructions
Note: The ~/
refers to your home directory:
Mac/Linux: /Users/yourusername/
Windows: C:\Users\yourusername\
(or use %USERPROFILE%
in Command Prompt)
Copy the standards files to ~/.agent-os/standards/
:
Copy the instruction files to ~/.agent-os/instructions/
:
Note: These instruction files work well as-is, but you're welcome to review and adjust them if needed.
Once you've installed the base files, you'll need to customize the standards files in ~/.agent-os/standards/
to match your preferences. This is where you define your way of building software.
With the base installation complete, now set up Agent OS for your AI tool:
Use the the following one-liner to run the Claude Code setup script:
curl -sSL https://raw.githubusercontent.com/buildermethods/agent-os/main/setup-claude-code.sh | bash
~/.claude/
folder. This points Claude Code to the instructions and standards located in your ~/.agent-os/
folder.~/.claude/commands/
folder.Copy the command files to ~/.claude/commands/
:
Copy claude-code/user/CLAUDE.md
to your system's ~/.claude/
folder
This points Claude Code to your default preferences and global standards.
That's it! You can now use these commands in Claude Code:
/plan-product
/create-spec
/execute-tasks
/analyze-product
Using Cursor? For each project where you want to use Agent OS, use the following one-liner to run the Cursor setup script:
Important: First be sure that you're inside your project's root folder so that Cursor rules are installed inside of it.
curl -sSL https://raw.githubusercontent.com/buildermethods/agent-os/main/setup-cursor.sh | bash
.cursor/rules/
directory in your project..cursor/rules/
folder with .mdc
extensions.mkdir -p .cursor/rules
Copy the command files to .cursor/rules/
and rename them with .mdc
extension:
plan-product.md
→ plan-product.mdc
create-spec.md
→ create-spec.mdc
execute-tasks.md
→ execute-tasks.mdc
analyze-product.md
→ analyze-product.mdc
That's it! You can now use these commands in Cursor:
@plan-product
@create-spec
@execute-tasks
@analyze-product
Using both Claude Code and Cursor? Follow both setups above to enable Agent OS in both tools.
Both tools will now work with the same Agent OS installation.
Agent OS is just markdown files. To adapt it for any AI tool, find where your tool looks for commands or context, then copy our command files there.
The command files simply point to the instructions and standards located in your ~/.agent-os/
installation.
Already have a product in development? Agent OS works great with existing code:
Complete steps 1 and 2 above for your tool.
Run the @analyze-product
command:
@analyze-product
I want to install Agent OS in my existing codebase
This will analyze your codebase, understand what's already built, and create Agent OS documentation that reflects your actual implementation.
After installation, you'll have:
Base Installation:
~/.agent-os/
├── standards/
│ ├── tech-stack.md # Your default tech choices
│ ├── code-style.md # Your formatting preferences
│ └── best-practices.md # Your development philosophy
└── instructions/
├── plan-product.md # Agent's instructions to initialize a product
├── create-spec.md # Agent's instructions to plan features
├── execute-tasks.md # Agent's instructions to build and ship
└── analyze-product.md # Agent's instructions to add to existing code
Claude Code Addition:
~/.claude/
├── CLAUDE.md # Points to your default preferences
└── commands/
├── plan-product.md # → points to ~/.agent-os/instructions/
├── create-spec.md # → points to ~/.agent-os/instructions/
├── execute-tasks.md # → points to ~/.agent-os/instructions/
└── analyze-product.md # → points to ~/.agent-os/instructions/
your-product/
├── .claude/
│ └── CLAUDE.md # Points to project details and instructions
└── .agent-os/
├── product/ # Created by plan-product
└── specs/ # Created by create-spec
Cursor Addition (Per Project):
your-product/
├── .cursor/
│ └── rules/
│ ├── plan-product.mdc # → points to ~/.agent-os/instructions/
│ ├── create-spec.mdc # → points to ~/.agent-os/instructions/
│ ├── execute-tasks.mdc # → points to ~/.agent-os/instructions/
│ └── analyze-product.mdc # → points to ~/.agent-os/instructions/
├── .agent-os/
│ ├── product/ # Created by plan-product
│ └── specs/ # Created by create-spec
└──CLAUDE.md # If also using Claude Code
With Agent OS installed, you're ready to supercharge your AI coding workflow. Here's how to use each part:
Before starting any project, customize your global standards to match how you like to build. Your agent will reference these standards constantly when planning projects and writing code, so make them reflect your actual preferences:
~/.agent-os/standards/tech-stack.md
Etc...
~/.agent-os/standards/code-style.md
Etc...
~/.agent-os/standards/best-practices.md
Etc...
💡 Pro tip: Be opinionated! The more specific your standards, the more consistent your agent's output.
When beginning a fresh codebase, you can provide as much or as little detail as you want—though more detail leads to better results by using the @plan-product
command.
@plan-product
I want to build a SaaS tool for tracking customer feedback
Key features: feedback collection, sentiment analysis, reporting dashboard
Target users: Product managers at B2B SaaS companies
Tech stack: Use my defaults
Note: When starting a new product, feel free to provide as much or as little detail in your initial prompt. You can even invoke the @plan-product
command with no other details and your agent will then prompt you for the specific details it needs to get started on your product's plan and roadmap.
Once your agent has collected the basic details it needs, it will:
.agent-os/product/
structureImportant: Review and edit the generated documentation to ensure it accurately reflects your vision and goals.
Have an existing codebase? No problem. Use the @analyze-product
command to install Agent OS into your existing codebase.
@analyze-product
I want to install Agent OS in my existing codebase
Your agent will:
Important: Review the generated documentation carefully—your agent's analysis might miss nuances or business context that only you know.
Ready to build something new? You have two options:
Option 1: Ask "what's next?"
Your agent should automatically trigger the @create-spec
command, check your product's roadmap.md file, and suggest the next uncompleted feature. You can confirm or adjust the feature before proceeding.
Option 2: Request a specific feature
Use the @create-spec
command along with your instructions or request for a new feature or task.
@create-spec
Let's add user authentication with email/password and OAuth
Either way, your agent will:
Important: This is the most critical review point! Carefully examine the SRD, specs, and especially the task breakdown. Adjust anything that doesn't match your expectations before proceeding.
Specs live in: .agent-os/specs/2025-07-16-user-authentication/
Time to code! Start building:
@execute-task
Work on the next task in the user authentication project
By default, your agent will complete one parent task and all its sub-tasks. You can adjust this:
Your agent will:
Important: While agents are great at following patterns, always review the code for business logic accuracy and edge cases before merging.
What's next on the roadmap?
Your agent checks .agent-os/product/roadmap.md
and suggests the next uncompleted feature.
@create-spec
Users report the dashboard is slow when filtering by date
Even for bug fixes, your agent creates a mini-spec with clear tasks.
@execute-task
Continue where we left off yesterday
Your agent reads the task list and picks up exactly where it stopped.
Agent OS gets better with use. Each spec teaches you something about your process, your preferences, and how to better guide your AI agents. Here's how to continuously improve your setup.
After each feature or spec, ask yourself:
tech-stack.md
- New tool preferences, version updatescode-style.md
- Formatting patterns, naming conventionsbest-practices.md
- Development philosophy, patterns to follow/avoidroadmap.md
- Adjust phases based on learningsdecisions.md
- Document why certain approaches work (or don't)tech-stack.md
- Override global standards when neededIf working with a team:
Remember: Agent OS is a living system. The goal isn't perfection on day one—it's continuous improvement. Each refinement makes your agents more effective and your codebase more consistent.
Your Agent OS a year from now will be dramatically better than today's, shaped by real experience and tailored to exactly how you and your team work best.
While Agent OS's task execution process automatically updates your roadmap and prompts for decision updates, it's good practice to regularly:
Regular maintenance keeps your Agent OS aligned with your evolving project and team needs.
Remember: The best time to fix issues is during planning, not after code is written!
Agent OS is a system for better planning and executing software development tasks with your AI agents. It consists of a set of finely tuned instructions, commands, and specs that you and your team can dial in to ensure your agents build the right things, the right way—your way.
Agent OS is free and open source, created by Brian Casel, the creator of Builder Methods.
Agent OS goes a few steps further than surface-level commands and project notes. There 3 specific ways Agent OS is different:
For more, see Why Agent OS?
Spec-driven development is a software development methodology that emphasizes the use of specifications to guide the development process—particularly in the age of building with AI coding agents.
It is a way to ensure that the software is built the right way—your way.Agent OS is free and open source, created by Brian Casel (that's me!).
I'm the creator of Builder Methods, where I teach fellow software designers and developers how to leverage AI to build better products, faster. Get my free Builder Briefing newsletter to get my latest insights and updates to help you grow as a professional in the age of building with AI.
You can subscribe to my YouTube channel, and connect with me on X, Blusky.
Builder Methods, is where I (Brian Casel) teach fellow software designers and developers how to leverage AI to build better products, faster. Get my free Builder Briefing newsletter to get my latest insights and updates to help you grow as a professional in the age of building with AI.
Absolutely!
Agent OS can be installed and adapted no matter which AI coding tool(s) you use. See the section on installing Agent OS in your tools for more details.
Yes — Coaching and courses for teams and individuals looking to get the most out of Agent OS, tought by me, Brian Casel (the creator of Agent OS).
Click here to learn more and inquire.
My best free training and resources are available through my Builder Briefing newsletter. You can also subscribe to my YouTube channel where I regularly release build-with-AI tutorials.
You'll also find just-in-time courses and coaching packages available from Builder Methods, here.
I'm happy to help! Shoot me (Brian Casel) an email using the form here.
Created by Brian Casel (that's me). I'm a career software developer, founder, and creator of Builder Methods and the Agent OS system for building with AI.