create_surface_based_element · Revit MCP: Risk & Policy

WHAT IT DOES

What create_surface_based_element does on Revit

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

WHY IT NEEDS A POLICY

Why create_surface_based_element needs a policy

The tool creates new architectural elements (floors, ceilings, roofs) in a Revit project, which is a Write operation—data modification that can theoretically be undone by deletion. It is not Destructive because creation is reversible (via delete_element tool).

From the tool's definition Tool name indicates 'create' action; description states 'Create one or more surface-based elements in Revit such as floors, ceilings, or roofs' and supports 'batch creation with detailed parameters'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_surface_based_element Rate-limited

create_surface_based_element 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": {
    "create_surface_based_element": {
      "limits": [
        {
          "counter": "create_surface_based_element_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about create_surface_based_element

What does the create_surface_based_element tool do? +

Create one or more surface-based elements in Revit such as floors, ceilings, or roofs. Supports batch creation with detailed parameters including family type ID, boundary lines, thickness, and level information. All units are in millimeters (mm). It is categorised as a Write tool in the Revit 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_surface_based_element? +

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

What risk level is create_surface_based_element? +

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

Can I rate-limit create_surface_based_element? +

Yes. Add a rate_limit block to the create_surface_based_element 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_surface_based_element completely? +

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

create_surface_based_element is provided by the Revit MCP server (mohamed-elnahla/revit-mcp-github-copilot). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.