claude-code-mechanism-selector

This skill helps you choose the right extension mechanism for Claude Code based on your requirements.

Quick Decision Guide

Ask these questions to determine the best mechanism:

1. Does it need to run deterministically (guaranteed, not AI-decided)?

• YES → Use Hooks (shell commands at lifecycle events)
• NO → Continue to question 2

2. Does it need a separate context window or specialized AI behavior?

• YES → Use Subagents (isolated context, custom system prompts)
• NO → Continue to question 3

3. Should it activate automatically based on context?

• YES → Use Skills (model-invoked, automatic discovery)
• NO → Use Slash Commands (user-invoked with /command)

Comparison Matrix

| Criteria | Slash Commands | Skills | Subagents | Hooks | |----------|---------------|--------|-----------|-------| | Invocation | User (/cmd) | Automatic | Automatic or explicit | System events | | Complexity | Single file | Multi-file | Separate context | Shell commands | | Control | Explicit | Context-based | Task-based | Deterministic | | Files | .md only | SKILL.md + resources | .md with frontmatter | JSON config | | Scope | Project or user | Project or user | Project or user | Project or user |

When to Use Each

Slash Commands

Best for quick, repeatable prompts you want explicit control over.

Examples:

• /review - Review code for bugs
• /explain - Explain code in simple terms
• /commit - Generate commit message

See commands.md for details.

Skills

Best for complex capabilities that should activate automatically.

Examples:

• PDF processing with scripts and templates
• Data analysis with reference documentation
• Code review with checklists and style guides

See skills.md for details.

Subagents

Best for specialized tasks requiring isolated context or custom AI behavior.

Examples:

• Code reviewer with specific review checklist
• Debugger with systematic debugging process
• Data scientist for SQL/BigQuery analysis

See subagents.md for details.

Hooks

Best for deterministic actions that must always happen.

Examples:

• Auto-format code after edits (PostToolUse)
• Log all bash commands (PreToolUse)
• Block edits to sensitive files (PreToolUse)
• Custom notifications (Notification)

See hooks.md for details.

Decision Examples

| Use Case | Best Mechanism | Why | |----------|---------------|-----| | "Format code after every edit" | Hooks | Deterministic, must always run | | "Quick prompt for code review" | Slash Command | Simple, explicit invocation | | "Comprehensive code review system" | Skill or Subagent | Complex, needs structure | | "Isolate research from main context" | Subagent | Needs separate context window | | "Auto-detect when to apply style guide" | Skill | Should activate automatically | | "Log all commands for compliance" | Hooks | Must run every time, deterministic | | "Block production file edits" | Hooks | Security rule, must be enforced |

Combining Mechanisms

These mechanisms complement each other:

• Skill + Subagent: Skill provides knowledge, subagent provides isolated execution
• Slash Command + Hook: Command triggers workflow, hook ensures formatting
• Subagent + Hook: Subagent does work, hook validates output