render_and_save_diagram · PlantUML MCP Server MCP

WHAT IT DOES

What render_and_save_diagram does on PlantUML MCP Server

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

WHY IT NEEDS A POLICY

Why render_and_save_diagram needs a policy

The tool creates or modifies files on the system by saving rendered diagrams. This is a Write operation (reversible file creation/modification) rather than Read (no data retrieval) or Execute (no arbitrary code execution indicated). Severity is medium because saving files could fill disk space or overwrite existing data, but the scope is limited to diagram artifacts without data deletion or system-level impact.

From the tool's definition Tool name 'render_and_save_diagram' indicates writing operations: 'render' (generate output) and 'save' (write to filesystem).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

render_and_save_diagram Rate-limited

render_and_save_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": {
    "render_and_save_diagram": {
      "limits": [
        {
          "counter": "render_and_save_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 MCP Server, so you can run agents against it safely.

FAQ

Questions about render_and_save_diagram

What does the render_and_save_diagram tool do? +

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

How do I enforce a policy on render_and_save_diagram? +

Register the PlantUML MCP Server MCP server in PolicyLayer and add a rule for render_and_save_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 MCP Server. Nothing to install.

What risk level is render_and_save_diagram? +

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

Can I rate-limit render_and_save_diagram? +

Yes. Add a rate_limit block to the render_and_save_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 render_and_save_diagram completely? +

Set action: deny in the PolicyLayer policy for render_and_save_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 render_and_save_diagram? +

render_and_save_diagram is provided by the PlantUML MCP Server MCP server (ka1lak/prompt2diagram-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.