Agent Config Editor
A complete system for creating, editing, and managing agent config files — CLAUDE.md, rules, skills, and more — for every AI tool you use.
Agent instruction files are how you teach AI tools about your project. They define build commands, coding conventions, architectural context, and the rules agents follow every session. Crystl gives you a dedicated system for every part of that workflow — from creating a file for the first time to keeping it optimized as your project grows.
The file chooser shows every supported file type with an icon and plain-English description of what it does. The block editor lets you build files from reusable sections you can drag to reorder, edit inline, or swap out for blocks from the library. And the project optimizer scans your project and surfaces exactly what's missing or needs attention.
Why it matters
Every AI tool covered
CLAUDE.md, AGENTS.md, codex.md, GEMINI.md, .cursorrules, .windsurfrules, copilot-instructions.md — one file chooser for all of them.
Block editor
Files open in a two-column editor: your content as draggable sections on the left, a reusable block library on the right. Drag to reorder, click to edit, insert from the library with one click.
Project optimizer
Scans for missing CLAUDE.md, oversized files, absent Build & Run sections, and more. Each finding explains why it matters and offers a one-click fix where possible.
Modular rules
Claude Rules let you split CLAUDE.md into focused files that Claude Code auto-discovers. Scope rules to specific directories so frontend rules don't load when you're working on backend code.
Ready to try it?
Create a free account and download Crystl for macOS.
get started getting started guide →Frequently asked questions
- What file types can I create?
- CLAUDE.md, CLAUDE.local.md, AGENTS.md, codex.md, GEMINI.md, .cursorrules, .windsurfrules, copilot-instructions.md. Plus Claude Code's extended config: rules, skills, and settings.
- What is the block editor?
- A two-column editor that breaks your file into logical sections (Build & Run, Architecture, Conventions, etc.). You can drag to reorder, click to edit inline, or toggle to raw text mode at any time.
- What are Claude Rules?
- Modular .claude/rules/*.md files that Claude Code auto-discovers and loads each session. Rules can be scoped to specific paths so they only load when you're working in the relevant part of your project.
- What does the line count indicator do?
- When editing CLAUDE.md, the editor footer shows a live count: green under 150 lines, yellow at 150–200, red over 200. Claude Code recommends staying under 200 lines for best performance.
- Does this work over SSH?
- Yes — file creation, template writing, rule setup, and the full block editor all work on remote projects over SSH.
More features
Gems & Shards
Gems, shards, and the Crystal Rail keep every project one click away.
Track Everything
See what every Claude session is doing at a glance.
Parallel Sessions
Run multiple Claude instances on the same repo without conflicts.
Conversation History
Every session is preserved. Scroll back through the full context anytime.
Prompt Integration
Facet Inserts give you one-click access to saved prompts, commands, and shortcuts.
Project Optimizer
Scan your project for gaps in agent configuration — missing files, incomplete docs, oversized code, and setup issues — with one-click fixes.
Starter Bundles
New gems launch with CLAUDE.md, rules, skills, and MCP config — all pre-configured from your bundle library.
Skills Library
Browse and import slash commands that teach Claude new tricks — code review, testing, deployment, and more.
Remote Development
Full Crystl integration over SSH — approval panels, file relay, and click-to-open on remote machines.
Crystl Quest
Assemble a party of specialized agents. Each brings unique skills, coordinates in shared chat, and executes in parallel.
Screenshot Bar
Drag recent screenshots into the terminal. Spotlight-powered, always up to date.