AgentSteer

Runtime protection for AI coding agents.

What it does

AgentSteer intercepts every tool call your AI agent makes via a PreToolUse hook, scores it against the task description, and blocks unauthorized actions before they execute. It catches prompt injection attacks, unauthorized file access, data exfiltration through delegation, and off-task behavior. Scoring uses oss-safeguard-20b (20B parameter model) via OpenRouter at under 200ms median latency.

Quick Start

pip install agentsteer

Set your OpenRouter API key. You can use a .env file or export it directly:

export OPENROUTER_API_KEY=sk-or-...

Install the hook for your framework:

agentsteer install claude-code

That's it. Every tool call is now scored and unauthorized actions are blocked.

How It Works

Agent makes tool call
        |
        v
PreToolUse hook intercepts the call
        |
        v
AgentSteer scores the action against the task description
(oss-safeguard-20b via OpenRouter, <200ms median)
        |
        v
Score >= threshold? ---> BLOCK (action never executes)
        |
        v
Score < threshold? ---> ALLOW (action proceeds normally)

Each action is evaluated against 4 security policies. If any policy is violated, the action is blocked and the agent receives feedback explaining why.

Supported Frameworks

Results

Evaluated on the AgentDojo benchmark, which tests whether agents can be tricked into executing prompt injection attacks hidden in their environment.

Median scoring latency: <200ms. Cost: $0.38 per 1M tokens via OpenRouter.

Full evaluation results and methodology at agentsteer.ai/evaluations.

Security Policies

A post-filter suppresses false positives from self-correction patterns (e.g., agent cancels a calendar event it just created in error).

Configuration

You can also run agentsteer setup for an interactive configuration wizard, or agentsteer login to connect to the AgentSteer cloud dashboard for real-time monitoring.

CLI Reference

agentsteer setup                # Interactive first-run setup
agentsteer install claude-code  # Install hook for Claude Code
agentsteer status               # Show current configuration
agentsteer score "task" "action" # Score a single action
agentsteer sessions             # List monitored sessions
agentsteer version              # Print version

Links

• Website: agentsteer.ai
• Documentation: agentsteer.ai/docs
• Evaluations: agentsteer.ai/evaluations
• Repository: github.com/AgentSteer/AgentSteer

License

MIT