Use allowedTools to Restrict What Claude Can Do in Sensitive Contexts

Sometimes you want Claude to analyze code without touching it, or you're running it in CI where certain operations should be off-limits. The allowedTools setting lets you control exactly which tools Claude can use.

{
  "permissions": {
    "allowedTools": ["Read", "Glob", "Grep", "Bash(git diff:*)"]
  }
}

Put that in .claude/settings.json and Claude can only read files, search, and run git diff commands — no editing, no writing, no arbitrary shell commands. Perfect for a read-only review mode.

On the command line, pass it directly:

claude --allowedTools "Read,Glob,Grep" -p "review src/ for security issues"

The tool names match Claude Code's built-in tools: Read, Write, Edit, Bash, Glob, Grep. You can also allow specific bash commands using patterns:

# Only allow running tests and reading files
claude --allowedTools "Read,Glob,Grep,Bash(npm test:*),Bash(php artisan test:*)"

This is especially useful in a few scenarios:

• CI pipelines — let Claude review code but not modify it
• Code audits — analysis only, no changes
• Onboarding — restrict new team members' Claude sessions to safe operations
• MCP tool control — allow specific MCP tools while blocking others

You can also use deniedTools for the inverse — allow everything except certain tools:

{
  "permissions": {
    "deniedTools": ["Bash(rm:*)", "Bash(git push:*)"]
  }
}

Full access is the default, but the safest Claude Code session is one where you've defined the boundaries upfront.

via Claude Code