proxy_clear_upstream

THE RISK

Medium Risk

Why proxy_clear_upstream needs a policy

This tool modifies the proxy configuration by removing the upstream proxy setting. It's a reversible configuration change (the upstream proxy can be re-added), so it falls under Write rather than Destructive. However, misuse could expose traffic that was previously routed through a secure/anonymizing proxy, making it a medium severity risk.

From the tool's definition Remove the global upstream proxy. Traffic will go directly to target servers.

Documented attack patterns abuse exactly the kind of access proxy_clear_upstream gives an agent:

POLICY

How to control proxy_clear_upstream

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "proxy_clear_upstream": {
      "limits": [
        {
          "counter": "proxy_clear_upstream_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

proxy_clear_upstream 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 Proxy — 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 Proxy tools

Destructive interceptor_docker_detach Remove proxy configuration from a Docker container and clean up injected files. Destructive proxy_clear_traffic Clear all captured traffic from the buffer. Destructive proxy_delete_session Delete a recorded session from disk. Destructive proxy_remove_host_upstream Remove a per-host upstream proxy override. Destructive proxy_remove_rule Delete an interception rule. Destructive proxy_session_stop Stop persistent on-disk capture and finalize the active session. Destructive interceptor_deactivate_all Kill ALL active interceptors across all types. Emergency cleanup — stops all browser insta Destructive interceptor_kill Kill a spawned process by target ID. Also retrieves final stdout/stderr output.

All 89 Proxy tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

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 proxy_clear_upstream

What does the proxy_clear_upstream tool do? +

Remove the global upstream proxy. Traffic will go directly to target servers. It is categorised as a Write tool in the Proxy MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on proxy_clear_upstream? +

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

What risk level is proxy_clear_upstream? +

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

Can I rate-limit proxy_clear_upstream? +

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

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

proxy_clear_upstream is provided by the Proxy MCP server (yfe404/proxy-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Proxy tool call.

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

CHECK YOUR STACK →