cordon_node · K8s MCP: Risk & Policy

WHAT IT DOES

What cordon_node does on K8s MCP

AI agents invoke cordon_node to trigger actions in K8s MCP. 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 cordon_node needs a policy

Cordoning a node triggers an external Kubernetes cluster operation that prevents new pods from being scheduled on that node. This is a significant operational action affecting cluster workload distribution, but it is reversible (via uncordon), placing it in Execute rather than Destructive. The blast radius is high because miscordoning nodes can disrupt workload scheduling across the cluster.

From the tool's definition Mark a node unschedulable (cordon)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cordon_node Rate-limited

cordon_node 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": {
    "cordon_node": {
      "limits": [
        {
          "counter": "cordon_node_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 K8s MCP, so you can run agents against it safely.

FAQ

Questions about cordon_node

What does the cordon_node tool do? +

Mark a node unschedulable (cordon). It is categorised as a Execute tool in the K8s MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on cordon_node? +

Register the K8s MCP server in PolicyLayer and add a rule for cordon_node: 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 K8s MCP. Nothing to install.

What risk level is cordon_node? +

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

Can I rate-limit cordon_node? +

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

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

cordon_node is provided by the K8s MCP server (rahul007-bit/k8s-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.