generate_plantuml_diagram · Plantuml MCP: Risk & Policy

WHAT IT DOES

What generate_plantuml_diagram does on Plantuml

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

WHY IT NEEDS A POLICY

Why generate_plantuml_diagram needs a policy

The tool creates or modifies files (diagram generation and optional local file saving), which is a reversible Write operation. It does not execute arbitrary code or shell commands—it only generates PlantUML diagrams based on provided syntax. The blast radius is minimal: worst case is creation of unwanted local files or consumption of disk space, which is easily remedied.

From the tool's definition Tool description states it 'Optionally saves the diagram to a local file' and 'Generate a PlantUML diagram', indicating file creation/modification capability.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

generate_plantuml_diagram Rate-limited

generate_plantuml_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": {
    "generate_plantuml_diagram": {
      "limits": [
        {
          "counter": "generate_plantuml_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 Plantuml, so you can run agents against it safely.

FAQ

Questions about generate_plantuml_diagram

What does the generate_plantuml_diagram tool do? +

Generate a PlantUML diagram with automatic syntax validation and error reporting for auto-fix workflows. Returns embeddable image URLs for valid diagrams or structured error details for invalid syntax that can be automatically corrected. Optionally saves the diagram to a local file. It is categorised as a Write tool in the Plantuml MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on generate_plantuml_diagram? +

Register the Plantuml MCP server in PolicyLayer and add a rule for generate_plantuml_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 Plantuml. Nothing to install.

What risk level is generate_plantuml_diagram? +

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

Can I rate-limit generate_plantuml_diagram? +

Yes. Add a rate_limit block to the generate_plantuml_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 generate_plantuml_diagram completely? +

Set action: deny in the PolicyLayer policy for generate_plantuml_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 generate_plantuml_diagram? +

generate_plantuml_diagram is provided by the Plantuml MCP server (plantuml-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.