flatten_hierarchy · Kicad MCP: Risk & Policy

WHAT IT DOES

What flatten_hierarchy does on Kicad

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

WHY IT NEEDS A POLICY

Why flatten_hierarchy needs a policy

The tool name suggests restructuring a hierarchical design by flattening it—a reversible modification of project structure. This aligns with the Write category (modifies data reversibly) rather than Execute or Destructive, as flattening can typically be undone via version control or undo.

From the tool's definition Tool name 'flatten_hierarchy' with sibling tools that perform structural modifications (add_hierarchical_sheet, add_hierarchical_label) on KiCad projects; context indicates write/modify operations on schematics and PCBs.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

flatten_hierarchy Rate-limited

flatten_hierarchy 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.

View as policy code

policy.json

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

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Kicad, so you can run agents against it safely.

FAQ

Questions about flatten_hierarchy

What does the flatten_hierarchy tool do? +

flatten_hierarchy. It is categorised as a Write tool in the Kicad MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on flatten_hierarchy? +

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

What risk level is flatten_hierarchy? +

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

Can I rate-limit flatten_hierarchy? +

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

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

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