modify_diagram · Arch7 MCP: Risk & Policy

WHAT IT DOES

What modify_diagram does on Arch7

AI agents use modify_diagram to create or update resources in Arch7 — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Arch7 environment.

WHY IT NEEDS A POLICY

Why modify_diagram needs a policy

This tool creates or modifies diagram data reversibly. Modifying an Excalidraw diagram changes its content but can be undone (diagrams are typically versioned or can be re-created). It does not delete data irreversibly (Destructive), execute arbitrary code (Execute), or create financial obligations.

From the tool's definition Tool name is 'modify_diagram' which indicates modification/mutation of existing diagrams. Server context describes tools for 'modifying...diagrams from structured input'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

modify_diagram Rate-limited

modify_diagram 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": {
    "modify_diagram": {
      "limits": [
        {
          "counter": "modify_diagram_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 Arch7, so you can run agents against it safely.

FAQ

Questions about modify_diagram

What does the modify_diagram tool do? +

modify_diagram. It is categorised as a Write tool in the Arch7 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on modify_diagram? +

Register the Arch7 MCP server in PolicyLayer and add a rule for modify_diagram: 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 Arch7. Nothing to install.

What risk level is modify_diagram? +

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

Can I rate-limit modify_diagram? +

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

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

modify_diagram is provided by the Arch7 MCP server (ktcrisis/arch7). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.