Rules

Rule packages provide guidelines, constraints, and best practices that shape how an AI coding assistant behaves in a project. Rules are the most widely supported package type across tools — most tools have a native concept of project rules.

For general information about rule packages, see Rule package type.

Claude Code

Auto-setup: No (manual placement) Target path:

.claude/rules/<rule-name>.md

File format: Markdown with YAML frontmatter.

Frontmatter fields used:

Field	Required	Description
name	No	Identifier for the rule
description	Yes	Short description of what the rule enforces
alwaysApply	No	If true, the rule is always active. If false or omitted, Claude loads it contextually based on the description
globs	No	File patterns that scope when the rule activates (e.g. **/*.ts)

Behavior: Users copy rule definition files into .claude/rules/. Claude Code loads rules based on alwaysApply and globs:

• alwaysApply: true — Rule is always included in Claude’s context.
• alwaysApply: false with globs — Rule activates when working with files matching the glob patterns.
• alwaysApply: false without globs — Rule is loaded contextually based on its description.

APKG installs rule packages but does not auto-copy files. After installation:

apkg add @acme/security-rules
cp apkg_packages/@acme/security-rules/security-standards.md .claude/rules/

Example definition file:

---
name: security-standards
description: Enforce security best practices
alwaysApply: true
---

When writing or reviewing code in this project, always:

- Never hardcode secrets, API keys, or credentials
- Validate and sanitize all user input
- Use parameterized queries for database access
- Apply the principle of least privilege for file and network access
- Flag any use of eval() or dynamic code execution

Cursor

Auto-setup: Yes Output path:

.cursor/rules/@<scope>/<name>.mdc

File format: Markdown with YAML frontmatter, saved as .mdc (Cursor’s rule format).

Frontmatter fields used:

Field	Required	Description
description	Yes	Cursor uses this for contextual matching
globs	No	File patterns that scope rule activation
alwaysApply	No	If true, rule is always active. If false, activated contextually

Behavior: Rules are a native concept in Cursor. APKG auto-generates .mdc files in .cursor/rules/. Cursor supports the same alwaysApply and globs scoping model, making rules the most portable package type between Claude Code and Cursor.

Key difference from Claude Code: Auto-setup is supported — no manual file copying needed.

Windsurf

Auto-setup: Yes Output path:

.windsurf/rules/@<scope>/<name>.md

Frontmatter fields used:

Field	Required	Description
description	Yes	Used for contextual matching
globs	No	File patterns that scope activation
alwaysApply	No	Controls auto-loading behavior

Behavior: Windsurf has native rule support similar to Cursor. APKG auto-generates rule files that Windsurf loads based on the same alwaysApply and globs scoping model.

Kiro

Auto-setup: Yes Output path:

.kiro/rules/@<scope>/<name>.md

Frontmatter fields used:

Field	Required	Description
description	Yes	Used for contextual matching
globs	No	File patterns that scope activation
alwaysApply	No	Controls auto-loading behavior

Behavior: Kiro supports project-level steering rules. APKG auto-generates rule files that Kiro loads based on description matching and glob scoping.

Codex

Auto-setup: No (manual placement) Target path:

AGENTS.md (appended) or .codex/@<scope>/<name>.md

Behavior: Codex reads AGENTS.md at the project root as its primary instruction source. It does not have a directory-based rule system like Cursor or Windsurf. Rule content must be manually appended to AGENTS.md or placed in .codex/.

Since Codex treats all instructions uniformly, rules lose their scoping features (alwaysApply, globs) — all content is always active.

Key difference: Codex has no rule-level scoping. Every rule is effectively alwaysApply: true.

Feature comparison

Feature	Claude Code	Cursor	Windsurf	Kiro	Codex
Auto-setup	No	Yes	Yes	Yes	No
alwaysApply support	Yes	Yes	Yes	Yes	No (always on)
globs scoping	Yes	Yes	Yes	Yes	No
description matching	Yes	Yes	Yes	Yes	No
Native rule concept	Yes	Yes	Yes	Yes	No (uses instructions)

Related pages

Page	Description
Rule package type	Manifest fields and package structure
Tool Setup Explained	Detection, precedence, and the generic setup mechanism