Medium Risk

create_hierarchical_subsheet

Create a new sub-sheet .kicad_sch file and link it into a parent schematic in a single call (create_schematic + add_hierarchical_sheet). The fastest way to grow a hierarchical design.

How to control create_hierarchical_subsheet ↓

What create_hierarchical_subsheet does on KiCAD-MCP-Server

AI agents use create_hierarchical_subsheet to create or update resources in KiCAD-MCP-Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your KiCAD-MCP-Server environment.

Medium Risk

Why create_hierarchical_subsheet needs a policy

This tool creates new data (a .kicad_sch file) and modifies existing data (the parent schematic) in a reversible manner. These are write operations. The changes can be undone by deleting the created file and removing the sheet reference, so it does not constitute a destructive operation.

From the tool's definition The tool description explicitly states it "Create[s] a new sub-sheet .kicad_sch file and link[s] it into a parent schematic" — it creates new files and modifies the parent schematic structure by adding a hierarchical sheet reference.

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

How to control create_hierarchical_subsheet

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "create_hierarchical_subsheet": {
      "limits": [
        {
          "counter": "create_hierarchical_subsheet_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

create_hierarchical_subsheet 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.

  1. Create a free account and register KiCAD-MCP-Server — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
LIMIT THIS TOOL →

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Related tools and policies

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Questions about create_hierarchical_subsheet

What does the create_hierarchical_subsheet tool do? +

Create a new sub-sheet .kicad_sch file and link it into a parent schematic in a single call (create_schematic + add_hierarchical_sheet). The fastest way to grow a hierarchical design. It is categorised as a Write tool in the KiCAD-MCP-Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_hierarchical_subsheet? +

Register the KiCAD-MCP-Server MCP server in PolicyLayer and add a rule for create_hierarchical_subsheet: 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 KiCAD-MCP-Server. Nothing to install.

What risk level is create_hierarchical_subsheet? +

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

Can I rate-limit create_hierarchical_subsheet? +

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

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

create_hierarchical_subsheet is provided by the KiCAD-MCP-Server MCP server (mixelpixx/kicad-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every KiCAD-MCP-Server tool call.

Start from KiCAD-MCP-Server, 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.

157 KiCAD-MCP-Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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