HOL Guard: Open-Source Antivirus for AI Agents

	Stop risky AI actions before they compromise your machine. HOL Guard is a local-first security layer for AI agents, tools, plugins, skills, MCP servers, and package installs. Install HOL Guard Read the documentation PyPI Package (hol-guard) Report an Issue

HOL Guard reviews agent actions before they run: shell commands, file access, package installs, and MCP tool calls. It detects secret exposure, destructive operations, prompt injection, and supply-chain risks, then allows, blocks, or requests approval according to your policy.

Run it locally without an account. Use the CLI and local dashboard to manage protection, resolve approvals, and inspect decision history. Optional Guard Cloud adds shared history, team policy, and fleet management.

Get started · Supported agents · Plugin scanner · Documentation · Contribute an extension · Development

Requires Python 3.10 or newer and pipx.

pipx install hol-guard
hol-guard init

The first-run wizard discovers supported agents and walks you through protection setup. It asks before each setup change, including opening the dashboard, installing agent integrations, and connecting optional cloud services.

Check your installation:

hol-guard --version
hol-guard status

To update an existing installation:

hol-guard update

For manual setup, see the installation guide. Release details and prereleases are on the releases page.

Guard connects through native agent hooks, managed MCP proxies, and launch integrations. Coverage depends on the events each agent exposes; the support matrix documents enforcement, approval delivery, and failure behavior per integration.

Codex, Claude Code, GitHub Copilot CLI, Cursor, Cline, Gemini CLI, Grok, Hermes, Kimi Code, Pi, oh-my-pi, OpenClaw, OpenCode, Antigravity, and ZCode.

For example, to set up Codex explicitly:

hol-guard install codex
hol-guard run codex --dry-run
hol-guard run codex

The dry run records the current artifact state before launch. For Codex, Guard installs native pre-tool hooks and refuses a managed launch if those hooks are missing or disabled.

Agent support matrix · Troubleshooting

Inspect the command's classification and matching rules:

hol-guard command test 'rm -rf ./build'
hol-guard command explain 'git clean -ndx'
hol-guard command extensions command.git --json

command test and command explain inspect the command without executing it or creating an approval. Use hol-guard approvals to resolve a pending request and hol-guard receipts to review the recorded decision.

The Extension directory lists command coverage generated from the runtime registry. External contributions require explicit opt-in; required core protections remain enabled. To add coverage, follow the Extension contribution guide.

hol-guard supply-chain sync
hol-guard supply-chain scan
hol-guard supply-chain explain minimist@1.2.5 --ecosystem npm

The package verdict includes the available advisory evidence and ecosystem coverage. See the get-started guide for package-manager interception and the remediation guide for handling false positives.

This repository also ships plugin-scanner, a CLI for maintainers who want security and quality checks before publishing agent plugins, skills, and MCP integrations.

pipx install plugin-scanner
plugin-scanner scan .
plugin-scanner lint .
plugin-scanner verify .

The scanner detects Codex, Claude Code, DeepSeek Harness, Gemini CLI, Kimi Code, and OpenCode package formats. Use plugin-scanner --list-ecosystems to list them or --ecosystem to select one. At a Codex marketplace root, it discovers local plugin entries automatically.

Checks cover manifests, secrets, MCP transport and command configuration, approval defaults, skills, dependency lockfiles, and GitHub Actions permissions. Optional Cisco integrations add skill and MCP analysis. Reports support text, JSON, Markdown, and SARIF.

plugin-scanner scan . --format sarif --output plugin-scanner.sarif
plugin-scanner scan . --fail-on-severity high

Quality grades use the checks applicable to each package. Trust scoring has separate provenance and weights; see the skill, MCP, and plugin scoring references.

Add the scanner to a plugin repository:

name: Plugin security
on: [push, pull_request]

permissions:
  contents: read

jobs:
  scan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
      - uses: hashgraph-online/ai-plugin-scanner-action@fdb49f9d85321a2ced2933301b395dd3c1ce9c8f # v1.2.631
        with:
          plugin_dir: "."
          min_score: 80
          fail_on_severity: high

See the action documentation for SARIF uploads, submission workflows, and machine-readable outputs. The action source is maintained in action/.

The baseline packages work without Cisco dependencies. To add Cisco skill scanning, use Python 3.11 through 3.14 and install the extra in an isolated environment:

pipx install 'plugin-scanner[cisco]'

For Cisco MCP analysis, use the repository's Docker image or the cisco-mcp dependency group:

uv sync --extra dev --extra cisco --group cisco-mcp --python 3.13
uv run plugin-scanner scan . --cisco-skill-scan on --cisco-mcp-scan on

The published cisco extra provides skill scanning; the separate cisco-mcp group supplies the MCP scanner. Dependency versions and Python constraints are maintained in pyproject.toml.

Use --ecosystem auto to detect supported packages in a repository, or select an ecosystem explicitly:

plugin-scanner scan ./plugins-repo --ecosystem claude
plugin-scanner scan ./dsh-plugin --ecosystem deepseek-harness

Plugin Scanner reports a quality grade alongside trust provenance. Quality scores are normalized across applicable checks, so optional surfaces do not inflate a package's grade.

Skill trust uses the HCS-28 baseline adapter IDs, weights, and denominator rules. MCP and Codex plugin trust use explicit adapters, weights, and contribution modes documented in the local specifications:

• Skill Trust Local Draft
• MCP Trust Draft
• Codex Plugin Trust Draft

# Structured security report
plugin-scanner scan ./my-plugin --format json --profile public-marketplace

# Inspect authoring rules
plugin-scanner lint ./my-plugin --list-rules
plugin-scanner lint ./my-plugin --explain README_MISSING

# Apply supported mechanical fixes
plugin-scanner lint ./my-plugin --fix --profile strict-security

# Verify package readiness; --online permits live probes
plugin-scanner verify ./my-plugin --format json
plugin-scanner verify ./my-plugin --online --format text

# Generate a submission artifact for one plugin
plugin-scanner submit ./my-plugin --profile public-marketplace --attest dist/plugin-quality.json

# Collect component diagnostics
plugin-scanner doctor ./my-plugin --component mcp --bundle dist/doctor.zip

For a repository marketplace, scan, lint, verify, and doctor can target the root. submit targets one plugin package.

The scanner recognizes Codex plugin manifests, interface metadata, declared assets, and marketplace packages:

• Local manifest paths use ./ prefixes; lint --fix preserves or adds them.
• .agents/plugins/marketplace.json is the preferred marketplace location, with root marketplace.json supported for compatibility.
• Interface validation checks declared links and assets without requiring an undocumented type field.
• verify --online checks HTTP remote reachability. Stdio server execution is skipped for manual review.

See the Codex plugin documentation and Model Context Protocol specification for upstream formats.

Configure the scanner in .plugin-scanner.toml:

[scanner]
profile = "public-marketplace"
baseline_file = "baseline.txt"
ignore_paths = ["tests/*", "fixtures/*"]

[rules]
disabled = ["README_MISSING"]
severity_overrides = { CODEXIGNORE_MISSING = "low" }

The GitHub Action requires trust_repository_policy: true before repository-owned configuration and baselines can change its verdict. Enable that option only for policy you intend the workflow to trust.

The AI Plugin Scanner Action supports security gates, SARIF uploads, submission intake, and registry payloads. Its source lives in action/, and the publication workflow distributes the action bundle.

The legacy HOL Codex Plugin Scanner Action remains available for existing workflows.

Use submission_enabled: true to open or reuse a submission issue when a plugin meets the configured threshold. submission_token must have permission to create issues in the target submission repository. The action emits submission status and issue URLs as outputs.

See the action's input reference for submission_score_threshold, submission_token, and the target repository options.

Set registry_payload_output to write a machine-readable payload for a registry or badge pipeline. The action also exposes score, grade, grade_label, max_severity, and findings_total outputs and can write a job summary.

The HOL Registry Broker plugin is an example of an agent plugin in the HOL Plugin Registry. Its registry listing provides current trust information.

AI agents can run commands, install dependencies, read files, and call external tools within one session. HOL Guard reviews those actions at supported execution points and keeps the policy decision, approval request, and receipt together.

Use it for AI agent security on a developer machine, MCP security around connected tools, and supply-chain checks for packages and plugins. Teams can add Guard Cloud for shared approvals and policy management while retaining local protection.

HOL Guard is open-source antivirus and runtime protection for AI agents. It reviews supported tool calls, shell commands, file access, and package operations for risks such as secret exposure, prompt injection, destructive actions, and malicious dependencies.

Yes. Local protection, CLI commands, approvals, and receipts work without signing in. Guard Cloud is optional and adds synchronized evidence, team controls, and fleet visibility. See Local Guard vs. Guard Cloud for the feature boundary.

Guard includes adapters for Codex, Claude Code, GitHub Copilot CLI, Cursor, Cline, Gemini CLI, Grok, Hermes, Kimi Code, Pi, oh-my-pi, OpenClaw, OpenCode, Antigravity, and ZCode. The support matrix explains which events and enforcement paths each adapter supports.

Install hol-guard to protect agent activity on your machine. Install plugin-scanner to inspect plugin packages and enforce security and quality checks in CI. This repository builds and publishes both distributions.

Guard inspects MCP server configuration and reviews supported MCP tool calls through agent hooks and managed proxies. Plugin Scanner checks MCP configuration and HTTP remote reachability; optional Cisco MCP analysis adds static security findings.

The action may need approval under your active policy, or its tools or artifacts may have changed. Start with hol-guard approvals, inspect the command with hol-guard command explain '<command>', and use hol-guard receipts to review the recorded decision.

Use the Extension Builder CLI to turn exported command metadata or an MCP tool inventory into contribution files and tests. It works offline: it reads the export without importing or running the target tool.

1. Propose the coverage. Check the Extension directory for existing coverage. For a new capability, open an Extension proposal with the proposed command.<name> ID, supported operations, destructive examples, safe counterparts, and upstream references. Extend an existing extension when it already owns the operation.

Follow the development setup, then run the examples below from your HOL Guard checkout. uv run --no-sync uses that checkout's installed development version.

2. Generate a contribution kit. This example uses the checked-in, synthetic samplectl inventory. For your own contribution, replace the input and metadata with your tool's export and public publisher details.

uv run --no-sync hol-guard extensions generate --from cli \
  --input docs/guard/extension-builder/examples/cli-surface.json \
  --slug samplectl --executable samplectl --name 'Sample CLI' \
  --publisher community.example --publisher-name 'Example Maintainer' \
  --homepage https://example.test/samplectl \
  --upstream-version 1.0.0 --output samplectl-kit

uv run --no-sync hol-guard extensions validate samplectl-kit

The output directory must be new, with an existing parent directory. The kit includes discovery.json, review.json, report.json, contribution metadata, a native detector, generated tests, and a file manifest.

Other inputs: --from help reads saved command help; --from click reads a Click Context.to_info_dict() export; --from oclif reads oclif.manifest.json; --from mcp reads a complete exported tools/list result; and --from snapshot replays discovery.json. The cli example above uses normalized guard.cli-surface.v1 JSON.

For MCP contributions, the generator uses --launcher and --package instead of --executable. See the MCP kit example for a complete command and pagination requirements.

3. Review the operations and regenerate. Read report.json and compare the discovered operations with the upstream implementation. Copy the review file before editing:

cp samplectl-kit/review.json samplectl-review.json

Edit samplectl-review.json, keeping its discovery binding and operation IDs intact. CLI operations use review or block; the root operation stays review. Set reviewed: true for entries you have assessed, with rationale and a public HTTPS evidence reference. Add safeArgv only for exact, verified safe invocations. The review format includes a complete entry example.

Recompile from the saved snapshot rather than editing generated detectors or manifests:

uv run --no-sync hol-guard extensions generate --from snapshot \
  --input samplectl-kit/discovery.json \
  --review samplectl-review.json --output samplectl-reviewed

uv run --no-sync hol-guard extensions validate samplectl-reviewed
uv run --no-sync hol-guard extensions diff samplectl-kit samplectl-reviewed

diff exits 0 for equal kits and 1 when valid kits differ. If the upstream export changes, generate and review a new snapshot.

4. Preview and apply the integration. On your contribution branch, preview the changes to the current checkout:

uv run --no-sync hol-guard extensions apply samplectl-reviewed --repo .

Inspect the listed paths and generated files. Copy the printed plan digest into the following command before running it:

uv run --no-sync hol-guard extensions apply samplectl-reviewed --repo . \
  --expected-plan THE_PRINTED_PLAN_DIGEST \
  --write

The write applies the reviewed plan to contribution files, the external trust map, catalog registration, packaging, and authoring ownership records. Existing IDs or conflicting files stop integration for review.

5. Test and submit a pull request. For the samplectl example:

uv run --no-sync python scripts/release/stage_guard_cloud_review_artifacts.py
uv run --no-sync pytest -q tests/test_generated_cli_samplectl_extension.py
uv run --no-sync pytest -q \
  tests/test_guard_extension_contribution.py \
  tests/test_guard_extension_trust.py \
  tests/test_guard_command_extension_registry.py
uv run --no-sync python scripts/render_command_extension_directory.py
uv run --no-sync python scripts/render_command_extension_directory.py --check
git diff --check

Use your generated test filename for a different slug. Add cases for destructive operations, safe previews, aliases, reordered flags, quoting, malformed input, and compound commands. Run lint and formatting checks on changed Python files. Inspect the final diff, commit the integration and regenerated directory, and open a PR against main linking the proposal and test results. Include the generated authoring records; keep scratch kit directories and raw upstream exports out of the PR.

Community contributions remain External and off by default. Tests must prove they are inert until a local administrator enables them. Generating, applying, or merging a contribution does not activate it, and its detector cannot weaken Guard's required protections.

Full builder reference · Contribution review requirements · External extension contract · Builder validation

Clone the repository and install the development dependencies with uv:

git clone https://github.com/hashgraph-online/hol-guard.git
cd hol-guard
uv sync --extra dev
uv run ruff check src tests
uv run ruff format --check src tests
uv run pytest --tb=short
uv build

For optional Cisco coverage, use the dependency group command above. See CONTRIBUTING.md for contribution requirements and the testing matrix for integration tests.

• HOL Plugin Registry
• HOL Plugin Security dataset on Hugging Face
• HOL Standards Documentation
• OpenAI Codex Plugin Documentation
• Model Context Protocol Documentation
• Cisco AI Skill Scanner
• Cisco AI MCP Scanner
• HOL GitHub Organization

Maintained by Hashgraph Online.

• Report a bug or request a feature
• Browse releases
• Explore the plugin security dataset

Licensed under Apache-2.0.