place_family

THE RISK

Medium Risk

Why place_family needs a policy

This tool creates new content (places a family instance) in the Revit model, which is a write/create operation. It modifies the model by adding geometry/elements, but this is reversible via undo in Revit. The severity is high because misuse could corrupt or significantly alter a BIM model used for architectural/engineering design and construction.

From the tool's definition Place a family instance at a specified location in the Revit model

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

POLICY

How to control place_family

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

policy.json

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

place_family 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.

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

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about place_family

What does the place_family tool do? +

Place a family instance at a specified location in the Revit model. It is categorised as a Write tool in the MCP server for Revit - Python MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on place_family? +

Register the MCP server for Revit - Python MCP server in PolicyLayer and add a rule for place_family: 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 MCP server for Revit - Python. Nothing to install.

What risk level is place_family? +

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

Can I rate-limit place_family? +

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

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

place_family is provided by the MCP server for Revit - Python MCP server (mcp-servers-for-revit/mcp-server-for-revit-python). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP server for Revit - Python tool call.

Start from MCP server for Revit - Python, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →