nav_back · Ruyipage MCP: Risk & Policy

WHAT IT DOES

What nav_back does on Ruyipage

AI agents invoke nav_back to trigger actions in Ruyipage. 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 nav_back needs a policy

This tool triggers a browser navigation action (history traversal), which is an external operation that changes the browser's state. It's not purely reading data — it actively controls the browser, which could cause side effects such as re-executing page scripts or losing form state. Browser automation actions fall under Execute.

From the tool's definition Go back in browser history

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

nav_back Rate-limited

nav_back 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": {
    "nav_back": {
      "limits": [
        {
          "counter": "nav_back_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 Ruyipage, so you can run agents against it safely.

FAQ

Questions about nav_back

What does the nav_back tool do? +

Go back in browser history. It is categorised as a Execute tool in the Ruyipage MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on nav_back? +

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

What risk level is nav_back? +

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

Can I rate-limit nav_back? +

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

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

nav_back is provided by the Ruyipage MCP server (neverl805/ruyipage_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.