Managing AGENTS.md
Overview
AGENTS.md is a README for AI agents. It tells any AI coding tool — Claude Code, Copilot, Cursor, Codex — how to navigate and work with your codebase. Keep it updated as the project evolves.
When to Create or Update
Create AGENTS.md when:
- •Setting up a new project or monorepo
- •Adding a significant new feature directory (5+ related files)
- •Introducing an extensible or polymorphic system
- •A codebase has no AGENTS.md and you're doing substantial work in it
Update AGENTS.md when:
- •Changing architectural patterns or project structure
- •Adding new build/test/deploy commands
- •Modifying base classes, registries, or extension points
- •Adding significant new directories
Do NOT create for:
- •Simple utility directories
- •Single-purpose modules
- •Non-extensible features
- •Directories with fewer than 5 related files
Tier Structure
For monorepos or large projects, use a hierarchical approach:
Root AGENTS.md → Project overview, tech stack, global conventions ├── app/AGENTS.md → App-specific architecture, commands, patterns │ └── feature/AGENTS.md → Feature-specific extension points
Each tier adds specificity. Agents read from root down to the most relevant file.
Template
# AGENTS.md — [Project or Directory Name] Brief one-line description of this part of the codebase. ## Commands \`\`\`bash npm run dev # Start development server npm test # Run tests npm run build # Production build \`\`\` ## Project Structure \`\`\` src/ ├── api/ # REST endpoints (~12 files) ├── services/ # Business logic (~8 files) ├── models/ # Data models (~6 files) └── utils/ # Shared utilities (~4 files) \`\`\` ## Key Patterns [Describe the main architectural patterns, data flow, or conventions] ## Boundaries ### Always - [Pattern to always follow] - [Convention to always use] ### Never - [Anti-pattern to avoid] - [Dangerous operation] ### Ask First - [Risky change that needs confirmation]
CLAUDE.md Companion
If the project also uses Claude Code, create a CLAUDE.md that imports the AGENTS.md:
@AGENTS.md ## Claude-Specific - [Any Claude Code-specific instructions, hooks, or skill references]
This avoids duplicating content while adding Claude-specific configuration.
Anti-Patterns
Stale documentation: An outdated AGENTS.md is worse than none. Update it when the code changes.
Too granular: Don't create AGENTS.md for every directory. Only for significant architectural boundaries.
Duplicating README: AGENTS.md is for AI agents, not humans. Focus on what an agent needs to navigate and modify code correctly — commands, patterns, boundaries.