Gemini CLI Hooks

Akto Guardrails for Gemini CLI provides security validation for AI interactions. It intercepts prompts before sending to Gemini and responses after generation, validates against security policies, blocks risky behavior, and reports events to your Akto dashboard.

Key Features

• ✅ Zero Installation - No standalone apps to install

• ✅ Transparent Integration - Uses Gemini CLI's native hook mechanism

• ✅ Real-time Protection - Validates every prompt and response

• ✅ Centralized Monitoring - All events reported to Akto dashboard

• ✅ Flexible Deployment - Supports Argus and Atlas modes (project or user-level)

• ✅ Configurable Behavior - Blocking or observation modes

How It Works

Gemini CLI's hook system executes custom scripts at two critical points:

2 Hook Points:

1. BeforeModel - Validates prompts before sending to Gemini API

2. AfterModel - Ingests prompt/response when Gemini finishes (final chunk)

File Structure

~/.gemini/
├── hooks/
│   ├── akto-validate-prompt-wrapper.sh       # Prompt validation wrapper
│   ├── akto-validate-prompt.py                # Prompt validation logic
│   ├── akto-validate-response-wrapper.sh      # Response ingestion wrapper
│   ├── akto-validate-response.py              # Response ingestion logic
│   └── akto_machine_id.py                     # Device ID utility
├── akto/
│   └── chat-logs/                             # Optional local logs
└── settings.json                              # Hook configuration

Key Files:

• Wrapper scripts (.sh): Set environment variables, invoke Python scripts

  • ⚠️ Contains AKTO_DATA_INGESTION_URL placeholder - Must be replaced with your Akto instance URL

• Python scripts (.py): Core validation logic and Akto API communication

• akto_machine_id.py: Generates unique device identifiers for Atlas mode

• settings.json: Links hooks to wrapper scripts

Note: Gemini CLI also supports project-level setup (.gemini/hooks/ and .gemini/settings.json in your project root). Config precedence: project → user → system.

Setup Guide

Prerequisites

• Gemini CLI installed and configured (Gemini CLI)

• Akto instance URL

• Python 3

• macOS, Windows or Linux with bash/zsh

Installation Steps

1

Create Directories

mkdir -p ~/.gemini/hooks
mkdir -p ~/.gemini/akto/chat-logs

2

Download Hook Scripts

# Base URL for downloading hooks
HOOKS_BASE="https://raw.githubusercontent.com/akto-api-security/akto/master/apps/mcp-endpoint-shield/gemini-cli-hooks"

# Download prompt validation hooks
curl -o ~/.gemini/hooks/akto-validate-prompt-wrapper.sh \
  "${HOOKS_BASE}/akto-validate-prompt-wrapper.sh"
curl -o ~/.gemini/hooks/akto-validate-prompt.py \
  "${HOOKS_BASE}/akto-validate-prompt.py"

# Download response ingestion hooks
curl -o ~/.gemini/hooks/akto-validate-response-wrapper.sh \
  "${HOOKS_BASE}/akto-validate-response-wrapper.sh"
curl -o ~/.gemini/hooks/akto-validate-response.py \
  "${HOOKS_BASE}/akto-validate-response.py"

# Download utility
curl -o ~/.gemini/hooks/akto_machine_id.py \
  "${HOOKS_BASE}/akto_machine_id.py"

# Make executable
chmod +x ~/.gemini/hooks/*.py ~/.gemini/hooks/*.sh

3

Configure Akto Ingestion URL ⚠️ CRITICAL STEP

All wrapper scripts contain placeholder {{AKTO_DATA_INGESTION_URL}} that must be replaced with your actual Akto instance URL.

Automated replacement:

# Set your Akto ingestion URL
AKTO_URL="https://your-akto-instance.com"

# Update all wrapper scripts
sed -i.bak "s|{{AKTO_DATA_INGESTION_URL}}|${AKTO_URL}|g" ~/.gemini/hooks/*-wrapper.sh

# Verify replacement
grep "AKTO_DATA_INGESTION_URL" ~/.gemini/hooks/*-wrapper.sh

Manual replacement (alternative):

Edit each wrapper script and replace:

AKTO_DATA_INGESTION_URL="{{AKTO_DATA_INGESTION_URL}}"

With:

AKTO_DATA_INGESTION_URL="https://your-akto-instance.com"

Files to update:

• akto-validate-prompt-wrapper.sh

• akto-validate-response-wrapper.sh

4

Configure Hooks

Create Gemini CLI settings configuration (user-level):

cat > ~/.gemini/settings.json << 'EOF'
{
  "hooks": {
    "BeforeModel": [
      {
        "matcher": "*",
        "hooks": [
          {
            "name": "akto-validate-prompt",
            "type": "command",
            "command": "bash ~/.gemini/hooks/akto-validate-prompt-wrapper.sh",
            "timeout": 10000,
            "description": "Validates prompts against Akto Guardrails"
          }
        ]
      }
    ],
    "AfterModel": [
      {
        "matcher": "*",
        "hooks": [
          {
            "name": "akto-validate-response",
            "type": "command",
            "command": "bash ~/.gemini/hooks/akto-validate-response-wrapper.sh",
            "timeout": 10000,
            "description": "Sends prompt/response pairs to Akto for ingestion"
          }
        ]
      }
    ]
  }
}
EOF

Note: Timeout is in milliseconds (10000 = 10 seconds). For project-level setup, use .gemini/settings.json and $GEMINI_PROJECT_DIR/.gemini/hooks/ in the command paths.

5

Configure Hook Behavior (Optional)

Edit wrapper scripts to customize:

# In each *-wrapper.sh file:

MODE="atlas"                    # "argus" or "atlas"
AKTO_SYNC_MODE="true"          # "true" (blocking) or "false" (observe only)
AKTO_TIMEOUT="5"               # Timeout in seconds
AKTO_CONNECTOR="gemini_cli"
GEMINI_API_URL="https://generativelanguage.googleapis.com"

Mode Options:

• Argus: Standard validation and reporting

• Atlas: Includes device-specific metadata

Sync Mode:

• true: Blocks threats

• false: Reports but allows execution

6

Verify Installation

Check logs to confirm hooks are working:

# View logs (if LOG_DIR is set)
tail -f ~/.gemini/akto/chat-logs/*.log

Test by running a Gemini command:

gemini

You should see log entries or hook activity. In Gemini CLI, use /hooks panel to view hook execution status.

Configuration Reference

Wrapper Script Variables

MODE="atlas"                                            # "argus" or "atlas"
AKTO_DATA_INGESTION_URL="{{AKTO_DATA_INGESTION_URL}}"  # ⚠️ MUST REPLACE
AKTO_SYNC_MODE="true"                                  # "true" or "false"
AKTO_TIMEOUT="5"                                       # Timeout in seconds
AKTO_CONNECTOR="gemini_cli"                            # Connector identifier
GEMINI_API_URL="https://generativelanguage.googleapis.com"

Environment Variables (Optional)

Override defaults via environment variables (e.g. in ~/.bashrc or ~/.zshrc):

export MODE="atlas"
export AKTO_DATA_INGESTION_URL="https://your-akto-instance.com"
export AKTO_SYNC_MODE="true"
export AKTO_TIMEOUT="5"

Managing Hooks (Gemini CLI)

Command	Description
/hooks panel	View hook execution status and recent output
/hooks enable-all	Enable all hooks
/hooks disable-all	Disable all hooks
/hooks enable <name>	Enable a specific hook
/hooks disable <name>	Disable a specific hook

Troubleshooting

Hooks Not Executing

# Check settings.json exists and is valid
cat ~/.gemini/settings.json | python3 -m json.tool

# Verify scripts are executable
ls -la ~/.gemini/hooks/
chmod +x ~/.gemini/hooks/*.py ~/.gemini/hooks/*.sh

# Check Gemini CLI and hook panel
gemini
# Then in CLI: /hooks panel

Ingestion URL Not Configured

# Check if placeholder still exists
grep "{{AKTO_DATA_INGESTION_URL}}" ~/.gemini/hooks/*-wrapper.sh

# Replace with actual URL
AKTO_URL="https://your-akto-instance.com"
sed -i.bak "s|{{AKTO_DATA_INGESTION_URL}}|${AKTO_URL}|g" ~/.gemini/hooks/*-wrapper.sh

Check Logs for Errors

# View logs (if LOG_DIR is set)
cat ~/.gemini/akto/chat-logs/*.log

# Check for errors
grep -i error ~/.gemini/akto/chat-logs/*.log 2>/dev/null || true

Events Not in Dashboard

# Test API connectivity
curl -X POST "${AKTO_DATA_INGESTION_URL}/api/v1/events" \
  -H "Content-Type: application/json" \
  -d '{"test": "event"}'

# Verify URL in wrapper scripts
grep "AKTO_DATA_INGESTION_URL" ~/.gemini/hooks/*-wrapper.sh

Hook Timing Out

Increase timeout in ~/.gemini/settings.json (value in milliseconds, e.g. "timeout": 120000). Ensure AKTO_DATA_INGESTION_URL is reachable.

Uninstallation

To completely remove Akto hooks from Gemini CLI:

Complete Removal

# 1. Remove hook configuration
rm ~/.gemini/settings.json

# 2. Remove Akto hook scripts
rm -rf ~/.gemini/hooks/

# 3. Remove Akto logs (optional - keeps historical data if skipped)
rm -rf ~/.gemini/akto/

# 4. No restart needed - Gemini CLI reads settings on each invocation

Selective Removal (Keep Logs)

If you want to preserve logs for audit purposes:

# Remove only hooks and configuration
rm ~/.gemini/settings.json
rm -rf ~/.gemini/hooks/

# Akto logs preserved in ~/.gemini/akto/

Backup Before Removal

# Backup configuration and logs before removal
mkdir -p ~/akto-backup
cp ~/.gemini/settings.json ~/akto-backup/gemini-settings.json.bak 2>/dev/null
cp -r ~/.gemini/akto/ ~/akto-backup/gemini-akto-logs/ 2>/dev/null

# Then proceed with removal steps above

Verify Removal

# Check that hooks are removed
test -f ~/.gemini/settings.json && echo "⚠️  settings.json still exists" || echo "✅ settings.json removed"
test -d ~/.gemini/hooks && echo "⚠️  Hook scripts still exist" || echo "✅ Hook scripts removed"

# Check if logs are removed (if you chose to remove them)
test -d ~/.gemini/akto && echo "ℹ️  Logs still present" || echo "✅ Logs removed"

Restore Gemini CLI to Default

After uninstallation, Gemini CLI will operate without Akto security monitoring. No additional configuration is needed beyond removing the files. Test with:

gemini

Enterprise Deployment

Automated Deployment Script

#!/bin/bash
# deploy-gemini-cli-hooks.sh

set -e
AKTO_URL="${1:-https://your-akto-instance.com}"

echo "🔧 Installing Akto Guardrails for Gemini CLI..."

# Create directories
mkdir -p ~/.gemini/hooks ~/.gemini/akto/chat-logs

# Download hooks
HOOKS_BASE="https://raw.githubusercontent.com/akto-api-security/akto/master/apps/mcp-endpoint-shield/gemini-cli-hooks"
curl -s "${HOOKS_BASE}/akto-validate-prompt-wrapper.sh" -o ~/.gemini/hooks/akto-validate-prompt-wrapper.sh
curl -s "${HOOKS_BASE}/akto-validate-prompt.py" -o ~/.gemini/hooks/akto-validate-prompt.py
curl -s "${HOOKS_BASE}/akto-validate-response-wrapper.sh" -o ~/.gemini/hooks/akto-validate-response-wrapper.sh
curl -s "${HOOKS_BASE}/akto-validate-response.py" -o ~/.gemini/hooks/akto-validate-response.py
curl -s "${HOOKS_BASE}/akto_machine_id.py" -o ~/.gemini/hooks/akto_machine_id.py

# Make executable
chmod +x ~/.gemini/hooks/*.py ~/.gemini/hooks/*.sh

# Configure URL
sed -i.bak "s|{{AKTO_DATA_INGESTION_URL}}|${AKTO_URL}|g" ~/.gemini/hooks/*-wrapper.sh

# Create settings.json
cat > ~/.gemini/settings.json << 'EOFSETTINGS'
{
  "hooks": {
    "BeforeModel": [
      {
        "matcher": "*",
        "hooks": [
          {
            "name": "akto-validate-prompt",
            "type": "command",
            "command": "bash ~/.gemini/hooks/akto-validate-prompt-wrapper.sh",
            "timeout": 10000,
            "description": "Validates prompts against Akto Guardrails"
          }
        ]
      }
    ],
    "AfterModel": [
      {
        "matcher": "*",
        "hooks": [
          {
            "name": "akto-validate-response",
            "type": "command",
            "command": "bash ~/.gemini/hooks/akto-validate-response-wrapper.sh",
            "timeout": 10000,
            "description": "Sends prompt/response pairs to Akto for ingestion"
          }
        ]
      }
    ]
  }
}
EOFSETTINGS

echo "✅ Installation complete!"
echo "📍 Akto instance: ${AKTO_URL}"
echo "Test with: gemini"

Deploy to developers:

curl -fsSL https://your-org.com/deploy-gemini-cli-hooks.sh | bash -s https://your-akto-instance.com

Quick Setup Summary

# 1. Create directories
mkdir -p ~/.gemini/hooks ~/.gemini/akto/chat-logs

# 2. Download all hook scripts from GitHub (see step 2 above)

# 3. ⚠️ Configure Akto URL (REQUIRED)
AKTO_URL="https://your-akto-instance.com"
sed -i.bak "s|{{AKTO_DATA_INGESTION_URL}}|${AKTO_URL}|g" ~/.gemini/hooks/*-wrapper.sh

# 4. Make executable
chmod +x ~/.gemini/hooks/*.py ~/.gemini/hooks/*.sh

# 5. Create settings.json (see step 4 above)

# 6. Test
gemini

Resources

• Gemini CLI: https://geminicli.com/

• GitHub: https://github.com/akto-api-security/akto

• Support: [email protected]

• Community: https://www.akto.io/community