🟡 Intermediate ⚙️ Type: Agent Harness / Claude Code Ecosystem 💸 Free & Open Source ⭐ 215,000+ GitHub Stars
What is ECC (Everything Claude Code)?
ECC (Everything Claude Code) is an open-source “agent harness performance optimization system” that has taken the developer world by storm. Created by Affaan Mustafa after winning an Anthropic hackathon, it has amassed over 215,000 stars on GitHub, making it the most popular configuration ecosystem for AI coding agents in existence.
Out of the box, tools like Claude Code and Cursor are brilliant but chaotic. If you tell them to “build a feature,” they often start blindly generating code without understanding your database schema, leading to massive refactors later. ECC fixes this by transforming your AI from an eager autocomplete tool into a highly disciplined, multi-agent engineering team.
It provides a massive, modular collection of Skills, Agents (subagents), Hooks, Commands, and Rules. When installed, it forces your AI to follow strict industry standards: evaluating security risks, reading the codebase before typing, performing Test-Driven Development (TDD), and running automated linters to fix its own errors.
Who is it for?
- Software Engineers using Claude Code, Cursor, or OpenCode who are tired of micromanaging their AI and correcting basic architectural mistakes.
- Engineering Managers looking to standardize how AI agents behave across their entire organization by enforcing strict rules for languages (like Go, Python, or Kotlin).
- Power Users who suffer from “context loss” during long AI sessions. ECC includes background hooks that automatically summarize and save session memory.
- Security-Conscious Coders who want their AI to run automated AgentShield security reviews before merging any pull requests.
What makes it special?
- Intent-Driven Development (IDD) — ECC fundamentally changes how you prompt. Using the
/feature-devcommand, the AI is forced into a 6-step workflow: Discovery, Codebase Exploration, Clarifying Questions, Architecture Design, Implementation, and Quality Review. It cannot write code until it defines verifiable acceptance criteria. - Massive Subagent Ecosystem — It includes over 60 specialized subagents. For example, if a Go build fails, the system automatically delegates the task to the
go-build-resolversubagent, which surgically fixesgo vetandstaticcheckerrors without touching your core logic. - NanoClaw Orchestration — A built-in orchestration layer that handles model routing (automatically picking the cheapest/fastest model for a sub-task), skill hot-loading, and continuous verification loops.
- Universal Package Manager Detection — Its background hooks are incredibly smart. They automatically detect whether your project uses
npm,pnpm,yarn, orbunand adjust the AI’s terminal commands accordingly.
Requirements before you start
To run this comprehensive harness system, your development environment must be prepared:
- Claude Code CLI — You must have Anthropic’s official terminal agent installed (or a compatible harness like Cursor/OpenCode).
- Node.js — Required to execute ECC’s background hook scripts securely.
- An Active API Key — You need an Anthropic, OpenAI, or OpenRouter API key with sufficient billing credits to power the multi-agent reasoning loops.
- Git — Required for version control operations and cloning the repository.
Step-by-step installation
ECC can be installed locally per project, but installing it globally via the Claude Code plugin marketplace is the easiest and most powerful method.
Step 1 — Add the Marketplace
Open your terminal and instruct Claude Code to add the ECC repository as an official plugin marketplace source:
/plugin marketplace add affaan-m/everything-claude-codeStep 2 — Install the Plugin
Run the installation command to download the core system into your global ~/.claude/ directory:
/plugin install everything-claude-code@everything-claude-code(Note: This will instantly grant your agent access to all 260+ workflow skills and hooks).
Step 3 — Run the Setup Wizard
Because ECC is massive, you don’t want every rule active at once. In your Claude Code prompt, simply type:
configure eccThis triggers ECC’s interactive AskUserQuestion wizard. The AI will ask you questions like: “Where should components be installed?” and “What is your tech stack?” It will then automatically trim away irrelevant skills (like Django rules if you are using Node) and optimize your local files.
Step 4 — Trigger a Workflow Command
To test the system, try using one of the new Slash commands instead of a normal prompt. Type:
/feature-dev "Add a password reset flow via email"Sit back and watch. Instead of immediately writing messy code, the agent will begin exploring your directory, scanning your database schema, and drafting an architecture blueprint for you to approve first.
Common errors and fixes
| Error | What it means | How to fix it |
|---|---|---|
Duplicate hook detection | You manually installed the hooks.json file but also installed the plugin. Modern versions of Claude Code load plugin hooks automatically, causing them to fire twice. | If you are using the plugin installation method, delete any manually copied hooks.json files from your local .claude/ directory. |
| Path reference errors after project-level install | You installed ECC directly into a specific project folder, but the markdown files are still pointing to the global ~/.claude/ paths. | Activate the setup wizard by typing configure ecc and tell it you want to “verify or fix an existing ECC installation.” It will rewrite the paths inside the markdown files to match your local directory. |
Subagents fail with command not found: staticcheck | ECC’s specialized agents attempt to use industry-standard linters and testing tools to verify their code, but those tools aren’t installed on your physical computer. | Claude Code runs on your host machine. You must manually install the required language tools (e.g., go install honnef.co/go/tools/cmd/staticcheck@latest) for the agent to use them. |
Free vs Paid comparison
| Feature | ECC (GitHub Open Source) | ECC Hosted App (ecc.tools) |
|---|---|---|
| Cost | $0 (Free forever) | $19 per month |
| Integration Type | ⚠️ Local terminal CLI install | 🟢 One-click GitHub App integration |
| Automated PR Reviews | ❌ Must run manually in terminal | ✅ Automated on every commit |
| Customization | ✅ Full access to edit agent markdown | Managed via web dashboard |
Bottom line: ECC has 215,000+ stars for a reason—it is the definitive masterclass in how to prompt and manage autonomous coding agents. If you rely on Claude Code or Cursor daily, taking 10 minutes to install this repository will save you hundreds of hours in frustrating AI refactoring. If you are managing a larger enterprise team, upgrading to their $19/mo hosted GitHub app brings these powerful AI guardrails directly to your team’s Pull Requests.
Alternatives — 3 similar tools
1. Claude Launchpad
A highly opinionated, alternative configuration suite for Claude Code. Rather than providing hundreds of granular skills like ECC, Launchpad focuses heavily on establishing a consistent developer experience with built-in sprint tracking, strict linting rules, and configuration scoring out of the box.
🔗 github.com/mboss37/claude-launchpad
2. Superpowers
Another massive enhancement suite for Claude Code. Where ECC focuses on structured, disciplined software engineering methodologies (like TDD and Intent-Driven Development), Superpowers focuses on injecting Claude with as many external capabilities and web-search tools as possible.
3. claude-code-templates
If you find the massive scale of ECC’s 260+ skills overwhelming, this repository offers a much more straightforward collection of templates. It provides basic, ready-made configurations for agents and hooks, making it easier to bootstrap a simple project without heavy multi-agent orchestration.
🔗 github.com/davila7/claude-code-templates
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