AI agents use hfss_set_variable to create or update resources in HFSS MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your HFSS MCP Server environment.
This tool creates or modifies design variables in an ANSYS HFSS project. These changes are reversible (variables can be deleted or updated to other values), making it a Write operation rather than Destructive. The severity is medium because incorrect variables could affect simulation validity and results interpretation, but the impact is confined to the simulation model itself without affecting external systems.
From the tool's definition Tool name 'hfss_set_variable' and description 'Set or update a design variable' indicate reversible modification of configuration data within the HFSS simulation environment.
Documented attack patterns abuse exactly the kind of access hfss_set_variable gives an agent:
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_set_variable:
{
"version": "1",
"default": "deny",
"tools": {
"hfss_set_variable": {
"limits": [
{
"counter": "hfss_set_variable_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}hfss_set_variable 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.
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Set or update a design variable. It is categorised as a Write tool in the HFSS MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the HFSS MCP Server MCP server in PolicyLayer and add a rule for hfss_set_variable: 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.
hfss_set_variable is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the hfss_set_variable 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.
Set action: deny in the PolicyLayer policy for hfss_set_variable. 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.
hfss_set_variable 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.
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.
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28 HFSS MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.