Create a netlist file in the MCP workdir and mark it as the currently loaded circuit.
AI agents use loadCircuit to create or update resources in Ltspice — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ltspice environment.
The tool creates a new file (netlist) and updates state by marking it as the loaded circuit. This is a reversible write operation — the file can be deleted and the state can be changed. No code execution, deletion, or financial action is involved.
From the tool's definition Create a netlist file in the MCP workdir and mark it as the currently loaded circuit.
Documented attack patterns abuse exactly the kind of access loadCircuit gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ltspice, and nothing reaches the server without passing your rules. This is the rule we recommend for loadCircuit:
{
"version": "1",
"default": "deny",
"tools": {
"loadCircuit": {
"limits": [
{
"counter": "loadcircuit_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}loadCircuit 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.
Free to start. No card required.
Create a netlist file in the MCP workdir and mark it as the currently loaded circuit. It is categorised as a Write tool in the Ltspice MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Ltspice MCP server in PolicyLayer and add a rule for loadCircuit: 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 Ltspice. Nothing to install.
loadCircuit 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 loadCircuit 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 loadCircuit. 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.
loadCircuit is provided by the Ltspice MCP server (xuio/ltspice-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ltspice, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
71 Ltspice tools catalogued and risk-classified — across an index of 43,000+ MCP servers.