update_gravity · Mcp Pihole MCP: Risk & Policy

WHAT IT DOES

What update_gravity does on Mcp Pihole

AI agents invoke update_gravity to trigger actions in Mcp Pihole. 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 update_gravity needs a policy

Rebuilding the gravity database is an execute-class operation: it runs a significant background process (gravity update) that re-downloads and reprocesses all blocklists, updating the DNS blocking database. While not irreversible in a destructive sense, misuse could temporarily disrupt DNS filtering, cause high network/CPU load, or corrupt the database if interrupted.

From the tool's definition 'Rebuild the gravity database' — this triggers an external operation that reprocesses and reconstructs Pi-hole's gravity blocklist database

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_gravity Rate-limited

update_gravity 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": {
    "update_gravity": {
      "limits": [
        {
          "counter": "update_gravity_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 Mcp Pihole, so you can run agents against it safely.

FAQ

Questions about update_gravity

What does the update_gravity tool do? +

Rebuild the gravity database. It is categorised as a Execute tool in the Mcp Pihole MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on update_gravity? +

Register the Mcp Pihole MCP server in PolicyLayer and add a rule for update_gravity: 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 Mcp Pihole. Nothing to install.

What risk level is update_gravity? +

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

Can I rate-limit update_gravity? +

Yes. Add a rate_limit block to the update_gravity 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_gravity completely? +

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

update_gravity is provided by the Mcp Pihole MCP server (obrien-matthew/mcp-pihole). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.