call_gateway_tool · MCP Gateway MCP: Risk & Policy

WHAT IT DOES

What call_gateway_tool does on MCP Gateway

AI agents invoke call_gateway_tool to trigger actions in MCP Gateway. 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 call_gateway_tool needs a policy

This is a meta-execution tool that can invoke any underlying tool registered in the MCP gateway. Its blast radius is effectively the union of all tools it aggregates, which could include Destructive, Financial, Execute, Write, or Read tools. Since the tool can trigger any arbitrary downstream operation depending on the arguments passed, it must be classified at the highest applicable severity.

From the tool's definition 调用 gateway 下某个真实工具 ("Call a real tool under the gateway") — executes arbitrary downstream tools with arbitrary arguments

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

call_gateway_tool Rate-limited

call_gateway_tool 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": {
    "call_gateway_tool": {
      "limits": [
        {
          "counter": "call_gateway_tool_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 Gateway, so you can run agents against it safely.

FAQ

Questions about call_gateway_tool

What does the call_gateway_tool tool do? +

调用 gateway 下某个真实工具。name 来自 search_gateway_tools / describe_gateway_tool，arguments 为该工具的真实参数字典。. It is categorised as a Execute tool in the MCP Gateway MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on call_gateway_tool? +

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

What risk level is call_gateway_tool? +

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

Can I rate-limit call_gateway_tool? +

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

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

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