merge_by_distance · Blender MCP: Risk & Policy

WHAT IT DOES

What merge_by_distance does on BlenderMCP

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

WHY IT NEEDS A POLICY

Why merge_by_distance needs a policy

The 'merge_by_distance' operation modifies mesh data in a reversible way—merged vertices can be undone via undo/redo. This is characteristic of Write operations (creates or modifies data reversibly). It does not delete permanently, execute arbitrary external code, or affect financial systems. Confidence is moderate (0.72) because the description is empty, requiring inference from context and sibling tools.

From the tool's definition Tool named 'merge_by_distance' in a 3D modeling context (Blender). The description is empty, but based on sibling tools (add_*_modifier, align_*) and the server's stated capability to 'manipulate objects' and 'execute Python scripts directly within the…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

merge_by_distance Rate-limited

merge_by_distance 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": {
    "merge_by_distance": {
      "limits": [
        {
          "counter": "merge_by_distance_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 BlenderMCP, so you can run agents against it safely.

FAQ

Questions about merge_by_distance

What does the merge_by_distance tool do? +

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

How do I enforce a policy on merge_by_distance? +

Register the Blender MCP server in PolicyLayer and add a rule for merge_by_distance: 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 BlenderMCP. Nothing to install.

What risk level is merge_by_distance? +

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

Can I rate-limit merge_by_distance? +

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

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

merge_by_distance is provided by the Blender MCP server (shirshovdim/retopoflow_blender_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.