check_license

THE RISK

Low Risk

Why check_license needs a policy

This tool retrieves and displays license information for packages without creating, modifying, deleting, or executing any code. It is purely informational and poses minimal security risk—even if invoked maliciously, it only returns publicly available package metadata.

From the tool's definition Tool name 'check_license' and description 'Check package license' indicate a query operation that retrieves license information from package metadata.

Documented attack patterns abuse exactly the kind of access check_license gives an agent:

POLICY

How to control check_license

PolicyLayer is an MCP gateway — it sits between your AI agents and Npmplus, and nothing reaches the server without passing your rules. This is the rule we recommend for check_license:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "check_license": {}
  }
}

check_license is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Npmplus — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Npmplus tools

Destructive remove_packages Remove npm packages Destructive clean_cache Clean package manager cache Write install_packages Install npm packages Write update_packages Update npm packages Read analyze_dependencies Analyze project dependencies (provide either cwd path or package.json content) Read audit_dependencies Audit dependencies for vulnerabilities (provide either cwd path or package.json content) Read check_bundle_size Check bundle size of a package Read check_outdated Check for outdated packages (provide either cwd path or package.json content)

All 16 Npmplus tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about check_license

What does the check_license tool do? +

Check package license. It is categorised as a Read tool in the Npmplus MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on check_license? +

Register the Npmplus MCP server in PolicyLayer and add a rule for check_license: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Npmplus. Nothing to install.

What risk level is check_license? +

check_license is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit check_license? +

Yes. Add a rate_limit block to the check_license rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block check_license completely? +

Set action: deny in the PolicyLayer policy for check_license. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides check_license? +

check_license is provided by the Npmplus MCP server (shacharsol/js-package-manager-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Npmplus tool call.

Start from Npmplus, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →