rpc_handle_call · Rpcclient MCP: Risk & Policy

WHAT IT DOES

What rpc_handle_call does on Rpcclient

AI agents invoke rpc_handle_call to trigger actions in Rpcclient. 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 rpc_handle_call needs a policy

This tool executes methods on stored handle objects from an iOS RPC server. 'Call a method' implies executing arbitrary operations on remote iOS objects, which could trigger a wide range of system-level actions depending on the handle. The effects are determined by the method called, making this an Execute-category tool with high severity due to the potential blast radius of executing arbitrary iOS RPC methods.

From the tool's definition Call a method or read callable attribute from a stored handle object

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

rpc_handle_call Rate-limited

rpc_handle_call 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": {
    "rpc_handle_call": {
      "limits": [
        {
          "counter": "rpc_handle_call_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 Rpcclient, so you can run agents against it safely.

FAQ

Questions about rpc_handle_call

What does the rpc_handle_call tool do? +

Call a method or read callable attribute from a stored handle object. It is categorised as a Execute tool in the Rpcclient MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on rpc_handle_call? +

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

What risk level is rpc_handle_call? +

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

Can I rate-limit rpc_handle_call? +

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

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

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