update_stack · Sceptre MCP: Risk & Policy

WHAT IT DOES

What update_stack does on Sceptre

AI agents use update_stack to create or update resources in Sceptre — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Sceptre environment.

WHY IT NEEDS A POLICY

Why update_stack needs a policy

Updating a CloudFormation stack modifies existing cloud infrastructure, which is a Write operation. However, it carries high severity because infrastructure changes can cause service disruptions, configuration drift, or unintended resource modifications across a potentially large blast radius of dependent services.

From the tool's definition Update an existing CloudFormation stack via Sceptre

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_stack Rate-limited

update_stack stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_stack": {
      "limits": [
        {
          "counter": "update_stack_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about update_stack

What does the update_stack tool do? +

Update an existing CloudFormation stack via Sceptre. It is categorised as a Write tool in the Sceptre MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_stack? +

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

What risk level is update_stack? +

update_stack is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_stack? +

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

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

update_stack is provided by the Sceptre MCP server (sceptre/sceptre-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.