stop_dev_server · Npm Dev MCP: Risk & Policy

WHAT IT DOES

What stop_dev_server does on Npm Dev

AI agents invoke stop_dev_server to trigger actions in Npm Dev. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why stop_dev_server needs a policy

Stopping a dev server is an executable action that halts an active background process. While not destructive (the process can be restarted), it is more severe than Write operations because it terminates running services, potentially disrupting ongoing work or dependent systems. The effect is immediate and externally observable, fitting the Execute category.

From the tool's definition Tool name 'stop_dev_server' and description 'npm run devプロセス停止' (stop npm run dev process) indicates termination of a running process.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stop_dev_server Rate-limited

stop_dev_server stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "stop_dev_server": {
      "limits": [
        {
          "counter": "stop_dev_server_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Npm Dev, so you can run agents against it safely.

FAQ

Questions about stop_dev_server

What does the stop_dev_server tool do? +

npm run devプロセス停止. It is categorised as a Execute tool in the Npm Dev MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stop_dev_server? +

Register the Npm Dev MCP server in PolicyLayer and add a rule for stop_dev_server: 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 Npm Dev. Nothing to install.

What risk level is stop_dev_server? +

stop_dev_server is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit stop_dev_server? +

Yes. Add a rate_limit block to the stop_dev_server 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 stop_dev_server completely? +

Set action: deny in the PolicyLayer policy for stop_dev_server. 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 stop_dev_server? +

stop_dev_server is provided by the Npm Dev MCP server (masamunet/npm-dev-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.