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Foil

An AI agent that monitors your AI agents

Developer Tools
Artificial Intelligence
YC Application

Hunted byMher TorjyanMher Torjyan

All observability tools simply log traces with no context. Foil reimagines how you deploy and maintain agents by learning your agents behavior and responsibilities. We call these agent profiles and they evolve as your agent runs. Hallucinations, behavioral drift, loops, grounding failures: caught automatically with context, not just logged. 🎁 Product Hunt Exclusive - 50% off Pro for 3 months with code FOILPH

Top comment

Hey PH! We built Foil because we realized we were spending more time monitoring our AI agents than actually building them. We had traces, dashboards, logs but making sense of it all was a full-time job. We were the bottleneck, manually reviewing thousands of traces to figure out why and when agents were stuck, hallucinating, etc.

So we asked: what if we reimagined the way AI agents are monitored?

Foil is essentially an AI agent whose job is to watch your other agents. It learns how each one behaves (we call these agent profiles), sets its own health checks (anchors), and flags problems with context not just "error rate went up" but why and what changed. A customer support bot and a code review agent get evaluated differently because they should be.

Here's what's under the hood:
πŸ‘οΈ Agent Profiles - Foil automatically learns each agent's behavior: tool patterns, error rates, traffic shape. A living baseline, not a static dashboard.
🎯 Anchors - Auto-generated health checks (e.g. "error rate < 5%") that evaluate every trace against the profile
πŸ”Ž Smart Search β€” Query across all your agents, traces, users, and models in natural language. Ask "which agent has the highest error rate?" and get an instant answer with charts
πŸ‘£ Tracing - Understand every decision your agent made
πŸ” Detection - Hallucinations, behavioral drift, loops, prompt injection, PII leakage, and RAG grounding failures - caught in real-time
πŸ“Š Metrics - Per-agent dashboards for cost, latency, quality, and usage over time
🧠 Feedback Loop - Mark false positives or confirm real issues. Foil learns from you and gets more accurate over time

πŸŽ‡ Multimodal support - We support all file types for Documents, Images, Audio, Video, Code which is used for agent training and semantic search.

🎁 Product Hunt Exclusive - 50% off Pro for 3 months with code FOILPH

Try it: run npx @getfoil/foil-js wizard --dir <where_agents_lives> --agent-name <name_for_agent> --agent-description <what_agent_does> --api-key <secret_special_key> in your project. It detects your framework and instruments your code automatically.

Ask us anything here!

Quick start example: github.com/getfoil/foil-examples

Comment highlights

How does Foil distinguish between intentional behavioral changes in an agent and problematic behavioral drift when updating its agent profiles over time?