create_diagram · Flowchart MCP: Risk & Policy

WHAT IT DOES

What create_diagram does on Flowchart MCP

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

WHY IT NEEDS A POLICY

Why create_diagram needs a policy

This tool creates a new diagram artifact (reversible action). It does not read existing data in a sensitive way, does not execute arbitrary code or external operations, does not delete data, and does not involve financial transactions. Creation of diagrams is a standard Write operation with minimal blast radius—worst case is cluttering the diagram namespace with unwanted diagrams, which can be deleted.

From the tool's definition Tool name 'create_diagram' and description 'Create a new flowchart diagram' indicates creation of new data structure without destructive side effects.

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 Flowchart MCP, so you can run agents against it safely.

FAQ

Questions about create_diagram

What does the create_diagram tool do? +

Create a new flowchart diagram. Returns diagram ID. It is categorised as a Write tool in the Flowchart MCP 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 Flowchart 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 Flowchart MCP. 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 Flowchart MCP server (zafer-liu/flowchart_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.