Tools & Hooks Integration

Custom Skills can access Claude Code's tool set and integrate with the Hooks system.

Tool List

Standard tools available to Skills:

Tool	Type	Description
Read	Read-only	Read files
Write	Write	Create/overwrite files
Edit	Write	Exact string replacement
Bash	Execute	Run shell commands
Glob	Read-only	File pattern matching
Grep	Read-only	Text search
WebFetch	Network	Fetch web content
WebSearch	Network	Search the internet

Configuring Tool Permissions

allowed-tools:
  - Read
  - Write
  - Edit

Principle: Only grant tools the Skill genuinely needs.

Read-Only Analysis Skill

allowed-tools:
  - Read
  - Bash    # Only for git log, npm ls, etc.

Code Generation Skill

allowed-tools:
  - Read
  - Write
  - Edit
  - Bash    # Run tests for verification

Hooks Integration

Hooks allow automatic actions on specific events.

Available Event Hooks

{
  "hooks": {
    "PreToolUse": {
      "bash": "echo 'About to run: $TOOL_NAME'"
    },
    "PostToolUse": {
      "bash": "npm run lint"
    }
  }
}

Skill + Hook Combo

Scenario: A code-gen Skill that auto-formats after every file write.

SKILL.md:

---
name: component-generator
description: Generate React components with tests and stories
allowed-tools: [Read, Write, Edit, Bash]
---

settings.json:

{
  "hooks": {
    "PostToolUse": [
      {
        "tool": "Write",
        "command": "npx prettier --write $FILE_PATH"
      }
    ]
  }
}

MCP Tools

If MCP servers are configured (e.g., CodeGraph), Skills can call MCP tools too.

# Skill using CodeGraph
name: code-explorer
description: Explore codebase structure using CodeGraph
allowed-tools:
  - Read
  - mcp__codegraph__codegraph_search
  - mcp__codegraph__codegraph_context

Security Best Practices

1. Never use wildcards in allowed-tools
2. Restrict Bash to specific commands (via settings.json permissions)
3. Sensitive operations (deploy, publish) should not be allowlisted
4. Hook commands run outside Claude Code's process — audit script safety

Next Steps

• Examples — Build a complete Skill from scratch