block_create_from_entities

THE RISK

Medium Risk

Why block_create_from_entities needs a policy

The tool creates a new drawing object (a block definition) from existing entities. This is a write operation—it modifies the drawing state by introducing new CAD constructs. It is not destructive because block definitions can be removed or replaced. It is not execute/shell-level code—it is a domain-specific CAD operation.

From the tool's definition Tool name contains 'create' and description states 'Create a new block definition from existing entities in the drawing.' This operation modifies the drawing by adding a new block definition, which is reversible (blocks can be deleted or redefined).

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

POLICY

How to control block_create_from_entities

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

policy.json

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

block_create_from_entities 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 AutoCAD MCP Pro — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

Related tools and policies

More AutoCAD MCP Pro tools

Destructive construction_clear Delete every entity on the CONSTRUCTION layer. Idempotent. Destructive drawing_purge Purge all unused objects (layers, blocks, linetypes, styles) from the drawing. Destructive entity_delete Permanently delete an entity by its handle. Destructive entity_delete_many Delete multiple entities in one call. Returns count of deleted entities. Destructive layer_delete layer_delete Destructive block_explode block_explode Execute drawing_audit Run an integrity audit on the drawing to detect and fix errors. Execute system_run_command system_run_command

All 108 AutoCAD MCP Pro tools →

Write tools on other servers

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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 block_create_from_entities

What does the block_create_from_entities tool do? +

Create a new block definition from existing entities in the drawing. It is categorised as a Write tool in the AutoCAD MCP Pro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on block_create_from_entities? +

Register the AutoCAD MCP Pro MCP server in PolicyLayer and add a rule for block_create_from_entities: 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 AutoCAD MCP Pro. Nothing to install.

What risk level is block_create_from_entities? +

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

Can I rate-limit block_create_from_entities? +

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

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

block_create_from_entities is provided by the AutoCAD MCP Pro MCP server (u-c4n/autocad-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every AutoCAD MCP Pro tool call.

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

CHECK YOUR STACK →