update_site · Fastly NGWAF MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_site does on Fastly NGWAF MCP Server

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

WHY IT NEEDS A POLICY

Why update_site needs a policy

This tool modifies site configuration within a WAF system, which is a reversible write operation affecting security-critical settings. While the changes are not permanent deletions (ruling out Destructive), they could impact multiple aspects of site security and traffic. Severity is high because misconfigured WAF rules could expose applications to attacks or block legitimate traffic.

From the tool's definition Tool name is 'update_site' with description 'Update site configuration'. The verb 'update' indicates modification of existing data (site configuration).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_site Rate-limited

update_site 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_site": {
      "limits": [
        {
          "counter": "update_site_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 Fastly NGWAF MCP Server, so you can run agents against it safely.

FAQ

Questions about update_site

What does the update_site tool do? +

Update site configuration. It is categorised as a Write tool in the Fastly NGWAF MCP Server 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_site? +

Register the Fastly NGWAF MCP Server MCP server in PolicyLayer and add a rule for update_site: 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 Fastly NGWAF MCP Server. Nothing to install.

What risk level is update_site? +

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

Can I rate-limit update_site? +

Yes. Add a rate_limit block to the update_site 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_site completely? +

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

update_site is provided by the Fastly NGWAF MCP Server MCP server (purpleax/fastlymcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.