Superagent + Claude Code Hooks

Secure Claude Code with Superagent hooks to validate and block malicious prompts before execution.

Introduction

Claude Code is a powerful AI coding assistant that can execute commands, read files, and make changes to your codebase. While this autonomy is incredibly useful, it also introduces potential security risks. What if a malicious prompt tricks Claude into executing dangerous commands? What if sensitive data accidentally gets exposed?

This is where Superagent comes in. By integrating Superagent with Claude Code's hooks system, you can validate every prompt before Claude processes it, blocking malicious or dangerous requests automatically.

In this guide, we'll walk through building a complete security solution using Claude Code's UserPromptSubmit hook and the Superagent API.

Prerequisites

Before you begin, you'll need:

Superagent Account: Sign up at app.superagent.sh
API Key: Once logged in, navigate to your dashboard and create a new API key (format: sa_...)
Claude Code: Installed and running on your machine
Node.js: Version 18 or higher for running the CLI

What are Claude Code Hooks?

Claude Code hooks are custom scripts that execute at specific points in the Claude Code lifecycle. They allow you to:

Validate prompts before Claude processes them
Add context to prompts automatically
Block dangerous operations before they execute
Log and audit all interactions

The UserPromptSubmit hook specifically fires whenever a user sends a prompt to Claude, making it the perfect place to implement security checks.

Configure Claude Code

Step 1: Install Superagent CLI

Terminal

npm i -g @superagent-ai/cli

Step 2: Hook Configuration Format

Claude Code hooks are configured in ~/.claude/settings.json. Here's the complete configuration:

~/.claude/settings.json

{
  "env": {
    "SUPERAGENT_API_KEY": "your_api_key_here"
  },
  "hooks": {
    "UserPromptSubmit": [
      {
        "matcher": "*",
        "hooks": [
          {
            "type": "command",
            "command": "superagent guard"
          }
        ]
      }
    ]
  }
}

Step 3: Restart Claude Code

Close and reopen Claude Code to load the new configuration.

How It Works

User sends a prompt to Claude Code
Claude Code triggers the hook before processing the prompt

Hook passes JSON to CLI via stdin:

Hook Input

{
  "prompt": "User's prompt text here",
  "session_id": "abc123",
  "cwd": "/current/working/dir"
}

CLI validates the prompt with SuperagentLM
CLI returns decision as JSON:
- If blocked: Returns {"decision": "block", "reason": "..."}
- If allowed: Returns success (exit code 0)
Claude Code processes the result:
- Blocked prompts are rejected with the reason shown to user
- Allowed prompts proceed normally

Next Steps

Explore PreToolUse hooks to validate Bash commands before execution
Build custom validators for your specific security policies
Integrate with SIEM for enterprise security monitoring
Create team policies with shared hook configurations

Happy coding, and stay secure! 🛡️