create-diagram · Lucid MCP: Risk & Policy

WHAT IT DOES

What create-diagram does on Lucid

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

WHY IT NEEDS A POLICY

Why create-diagram needs a policy

This tool creates new diagrams in a user's Lucid account, which is a write operation that modifies the user's workspace by adding new data. The action is reversible (diagrams can be deleted), so it does not qualify as Destructive. It is not Financial, does not execute arbitrary code, and is not merely Read.

From the tool's definition Tool description states 'Create a new Lucid diagram' and 'the document is created in your Lucid account', indicating data creation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create-diagram Rate-limited

create-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": {
    "create-diagram": {
      "limits": [
        {
          "counter": "create-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 Lucid, so you can run agents against it safely.

FAQ

Questions about create-diagram

What does the create-diagram tool do? +

Create a new Lucid diagram from Standard Import JSON. Author JSON describing pages, shapes, and lines (no Mermaid); the document is created in your Lucid account and the edit URL is returned. Use for flowcharts, org charts, UML, BPMN, and cloud architecture diagrams. It is categorised as a Write tool in the Lucid 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-diagram? +

Register the Lucid MCP server in PolicyLayer and add a rule for create-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 Lucid. Nothing to install.

What risk level is create-diagram? +

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

Can I rate-limit create-diagram? +

Yes. Add a rate_limit block to the create-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 create-diagram completely? +

Set action: deny in the PolicyLayer policy for create-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 create-diagram? +

create-diagram is provided by the Lucid MCP server (lucid-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.