gateway.update_server

THE RISK

Medium Risk

Why gateway.update_server needs a policy

This tool modifies subordinate server packages and their connection state. While updates are generally reversible (packages can be downgraded or rolled back), the action directly alters deployed infrastructure state and could introduce breaking changes or service disruptions.

From the tool's definition Tool description states 'Update a subordinate MCP server package to latest version and reconnect it.' The actions are 'update' (modify) and 'reconnect' (reconfigure), which are reversible changes to server state and packages.

Documented attack patterns abuse exactly the kind of access gateway.update_server gives an agent:

POLICY

How to control gateway.update_server

PolicyLayer is an MCP gateway — it sits between your AI agents and PMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for gateway.update_server:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "gateway.update_server": {
      "limits": [
        {
          "counter": "gateway.update_server_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

gateway.update_server 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.

Create a free account and register PMCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More PMCP tools

Destructive gateway.disconnect_server Disconnect a running downstream MCP server without changing persistent config. Execute gateway.tasks_cancel Cancel a downstream MCP task by opaque task ID. Execute gateway.connect_server Connect or start a known downstream MCP server by name. Execute gateway.invoke Invoke a tool on a downstream MCP server. Execute gateway.provision Provision (install and start) a specific MCP server from the manifest. Execute gateway.restart_server Restart a known downstream MCP server without changing persistent config. Execute gateway.refresh Reload backend MCP server configurations and reconnect. Execute gateway.request_capability Find and auto-provision the right tool for a task — describe what you need in natural lang

All 26 PMCP tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about gateway.update_server

What does the gateway.update_server tool do? +

Update a subordinate MCP server package to latest version and reconnect it. It is categorised as a Write tool in the PMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on gateway.update_server? +

Register the P MCP server in PolicyLayer and add a rule for gateway.update_server: 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 PMCP. Nothing to install.

What risk level is gateway.update_server? +

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

Can I rate-limit gateway.update_server? +

Yes. Add a rate_limit block to the gateway.update_server 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 gateway.update_server completely? +

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

gateway.update_server is provided by the P MCP server (viperjuice/pmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every PMCP tool call.

Start from PMCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →