hfss_stop_app

THE RISK

High Risk

Why hfss_stop_app needs a policy

This tool triggers an external operation (stopping the HFSS application) whose side effects depend on the application state at invocation time. While not destructive in the sense of deleting user data, it forcibly terminates a running process and releases resources, which could interrupt ongoing simulations or operations.

From the tool's definition Tool name 'hfss_stop_app' and description 'Stop/Close HFSS application and release resources' indicate termination of an external application process.

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

POLICY

How to control hfss_stop_app

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "hfss_stop_app": {
      "limits": [
        {
          "counter": "hfss_stop_app_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

hfss_stop_app 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.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More HFSS MCP Server tools

Destructive hfss_delete_variable Delete a design variable Execute hfss_launch_app Launch a new HFSS application with GUI (creates new session) Execute hfss_restart_app Restart HFSS application Execute hfss_run_analysis Run simulation analysis Execute hfss_start_app Connect to existing HFSS application (no new session created) Write hfss_assign_radiation_boundary Assign a radiation boundary to a face Write hfss_assign_wave_port Assign a wave port to a face Write hfss_close_project Close current project (session stays active)

All 28 HFSS MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

High-risk tools in HFSS MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about hfss_stop_app

What does the hfss_stop_app tool do? +

Stop/Close HFSS application and release resources. It is categorised as a Execute tool in the HFSS MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on hfss_stop_app? +

Register the HFSS MCP Server MCP server in PolicyLayer and add a rule for hfss_stop_app: 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 HFSS MCP Server. Nothing to install.

What risk level is hfss_stop_app? +

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

Can I rate-limit hfss_stop_app? +

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

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

hfss_stop_app is provided by the HFSS MCP Server MCP server (leonardwy/hfss_mcpserver). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every HFSS MCP Server tool call.

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

CHECK YOUR STACK →