AgentFox

Know when your AI agent should stop.

An open-source control plane that checks what your agent may read, may claim and may do — and refuses the rest. It holds after the model has already been convinced.

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Docs · Getting started · Architecture · Contributing · What is built · Discussions

What it does

AgentFox sits on your agent's model and tool calls, in-process or as an HTTP gateway, and decides whether each one may happen. Every tool carries a declared impact tier, every agent holds explicit capability grants with argument limits, and every argument carries the provenance of where its value came from. A transfer whose recipient came out of a retrieved document is refused because of where the value came from, not because a detector recognised the payload. Every decision lands in a tamper-evident audit chain that an auditor can verify without trusting us.

Quickstart

pip install agentfox
agentfox init && agentfox demo

init creates a SQLite database and loads 43 controls and the policy packs, in about a second. demo runs a thirteen-step walkthrough in about five. Both are offline: no API key, no downloaded weights, no network egress. Or scan the directory you are in without installing:

curl -fsSL https://raw.githubusercontent.com/architsharm/agentfox/main/scripts/quickscan.sh | bash

Then govern your own agent with one line:

import agentfox
agentfox.auto()

Every OpenAI, Anthropic, LiteLLM and LangChain call in the process is traced, evaluated and audited, and every tool call in a response is checked before your code can run it. Nothing is blocked by the line itself: content policies start in observe, and tool containment enforces after agentfox init, raising agentfox.Blocked for a refused call.

Contain a tool call

Any language can ask the gateway about one call before running it:

agentfox serve                              # gateway + control-plane API on 127.0.0.1:8080
agentfox admin users create you@example.com --token   # first operator + API token, shown once

curl -s -X POST http://localhost:8080/v1/guard/tool_call \
  -H "Authorization: Bearer $AGENTFOX_TOKEN" -H "Content-Type: application/json" \
  -d '{"agent":"payments-ops","tool":"payments.transfer",
       "arguments":{"amount":250,"currency":"USD","to":"acct_991"},
       "provenance":{"to":"tool_result","amount":"user"},
       "intent":"refund a duplicate charge"}' | jq '{verdict, approval_id}'

{ "verdict": "escalate", "approval_id": "apr_01m376q43zby33tbsp" }

The recipient came from a tool result, so the transfer waits for a human. Flip "to" to "user" and the same call returns allow. Once a person approves it (agentfox permit approvals approve apr_…), the same call with "approval_id" added runs, once. Pointed at /v1 as an OpenAI or Anthropic base URL, the gateway proxies model calls too, and a held one returns HTTP 428 with its approval_id. LangGraph, MCP, Claude Code hooks, the SDK and the full command set are in the website guides and the product tour.

Tracking without anyone running a command

A scan is a snapshot. Connect a GitHub repository, a hosted API's OpenAPI document or an MCP server once and AgentFox keeps re-checking it: every few hours, and on every push once the GitHub webhook is registered. What changed since the last run becomes a finding, and the finding closes itself when the condition clears. Setup and every finding type: Monitor connected sources.

What we measured

We do not claim adversarial robustness, and we do not believe anyone can. The Attacker Moves Second (Nasr, Carlini, Schulhoff et al., 2025) reports over 90% attack success against twelve published defences once the attacker adapts. So the number we lead with does not depend on catching anything: both rows below were measured with every detector switched off.

The cost is benign utility: when provenance is inferred, a legitimate action that copies a value out of a tool output looks the same as an attack, and it is escalated.

Optionally, detection gets better. The judgment tiers are off by default; with them on, agentfox catches 160/165 of the injection payloads that defeated our own pattern detectors, at 94.7% precision against the NotInject over-defense set. What each tier is worth, and what it costs.

Where we are still improving

Detection is the layer we trust least, so we publish its numbers.

• The default heuristic detector's held-out injection recall is 16.7%, at 100% precision (REPORT.md). An adaptive attacker that reads our verdict and retries gets 74% of the attacks we catch through within 50 attempts against the default stack.
• The deterministic answerability classifier abstains on 57/676 contested questions; with a judgment tier that becomes 572/676, at the cost of over-refusal rising from 0.75% to 6.8%.
• Against a real, independently installed llm-guard on indirect injection via tool output, it is more precise than us: 81.8% against our 66.7% on the same 20 cases, though of the 10 attacks among them we catch all 10 and it catches 9 (agent_security).
• On AgentDojo, per-argument taint misses 61 of 702 attacker write calls; session-level taint misses none of them and escalates three in four benign tasks.
• The opt-in classifier ensemble reaches 86.4% and 98.6% recall on two independent datasets, but it is not the shipped default: on long prompts it mostly times out.

Treat every detection number as a speed bump that raises attacker cost, never as a defence.

Not built yet

• It is only as good as your declarations. A destructive tool declared read is treated as read. agentfox doctor grades this; agentfox scan finds undeclared tools.
• You declare the estate yourself. No Okta, no DataHub; principals and grants live in AgentFox.
• Compliance mappings are DRAFT, not reviewed by counsel, and labelled so in every export.
• Version 0.3. No live IdP or SSO, single-org multi-tenancy enforced at the session, text only.

Live per-capability status, computed by probe: docs/status.md.

Documentation

Questions and ideas go to Discussions; bugs to Issues. New contributors: start with a good first issue.

Licence

Apache-2.0. All of it, and it stays that way: no licence key, no gated features.