model_combine

THE RISK

Medium Risk

Why model_combine needs a policy

This tool creates a new combined model by merging existing models together. It is a write/create operation — producing a unified artifact from multiple sources. It does not delete or overwrite the source models (no indication of destructive behavior), does not execute code, and has no financial implications.

From the tool's definition Merge multiple DEXPI models into one combined model. Combines all tagged plant items, instrumentation, and piping from source models.

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

POLICY

How to control model_combine

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

policy.json

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

model_combine 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 Engineering MCP Server — 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

Related tools and policies

More Engineering MCP Server tools

Destructive layout_delete Delete a layout from the store Execute layout_compute Compute layout for a model using ELK. Produces orthogonal edge routing suitable for P&ID d Execute model_batch_apply Execute multiple operations in a single call for efficiency Execute rules_apply Apply validation rules and return structured issues for LLM processing. Optionally auto-fi Write area_deploy Deploy a template into a model (STRATEGIC operation - replaces 50+ atomic calls) Write model_tx_begin Start a transaction on a model for atomic multi-operation changes Write model_load Import a model from various formats (JSON, Proteus XML, SFILES string) - Replaces dexpi_im Write project_init Initialize a new git-tracked project for engineering models

All 72 Engineering MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

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 model_combine

What does the model_combine tool do? +

Merge multiple DEXPI models into one combined model. Combines all tagged plant items, instrumentation, and piping from source models. It is categorised as a Write tool in the Engineering 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 model_combine? +

Register the Engineering MCP Server MCP server in PolicyLayer and add a rule for model_combine: 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 Engineering MCP Server. Nothing to install.

What risk level is model_combine? +

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

Can I rate-limit model_combine? +

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

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

model_combine is provided by the Engineering MCP Server MCP server (puran-water/dexpi-sfiles-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 Engineering MCP Server tool call.

Start from Engineering MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →