run_build · Node Dev MCP Server MCP: Risk & Policy

WHAT IT DOES

What run_build does on Node Dev MCP Server

AI agents invoke run_build to trigger actions in Node Dev MCP Server. 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 run_build needs a policy

This tool triggers execution of a build script, whose effects depend entirely on what the build script contains. Build scripts commonly invoke compilers, package managers, external services, and arbitrary shell commands. While not inherently destructive or financial, execution is uncontrolled and could produce wide-ranging effects (file modifications, network calls, process spawning).

From the tool's definition Tool name is 'run_build' and description states it 'Run the build script in the workspace'. The server description explicitly mentions 'execute build or dependency scripts'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

run_build Rate-limited

run_build 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": {
    "run_build": {
      "limits": [
        {
          "counter": "run_build_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 Node Dev MCP Server, so you can run agents against it safely.

FAQ

Questions about run_build

What does the run_build tool do? +

Run the build script in the workspace. It is categorised as a Execute tool in the Node Dev MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_build? +

Register the Node Dev MCP Server MCP server in PolicyLayer and add a rule for run_build: 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 Node Dev MCP Server. Nothing to install.

What risk level is run_build? +

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

Can I rate-limit run_build? +

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

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

run_build is provided by the Node Dev MCP Server MCP server (liamcarver/node-dev-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.