check-package

One call before npm install or pip install. Available as an MCP tool on Jeevesus and used by the Checks Action.

{ "ecosystem": "npm", "name": "@x402/svm", "version": "2.22.0" }

{
  "ecosystem": "npm",
  "package": "@x402/svm",
  "version": "2.22.0",
  "malicious": false,
  "verdict": "review",
  "reason": "Not malicious, but version 2.22.0 is below a security fix the maintainer shipped without an advisory (fixed in 2.23.0): ...",
  "advice": "Upgrade to 2.23.0 or later. OSV, npm audit and pip-audit will not flag this version, because no advisory exists."
}

Verdicts

Verdict	Means	Agent instruction
block	The package (or this version) is on the malicious-package deny-list, or its registry reputation looks like a staging package	Refuse to install and say why
review	Not malicious, but this version has published vulnerabilities, or sits below a security fix shipped without an advisory, or reputation is unusual	Prefer a fixed version; ask a person
allow	No evidence against it today	Install; still pin the version

Always pass version. Without it, only the name is checked: version-scoped entries and known vulnerabilities cannot be evaluated.

What it checks

1. The malicious-package deny-list (mostly OSV malicious-package records, version-aware).
2. Registry reputation: whether the package exists, its age and its download volume.
3. Published vulnerabilities for that exact version (OSV).
4. A short, cited list of security fixes shipped without any advisory, which no vulnerability database can flag.

allow means none of these hold anything against the package today. A package published an hour ago by an attacker can look exactly like that.

A prompt for your agent

Before installing any npm or PyPI dependency, call check-package with its ecosystem, name and exact version. If the verdict is block, do not install it and report the reason. If it is review, stop and ask me.

For CI, mirror the list with the packages feed or use the Checks Action.