generate_diagram · StarUML MCP Server MCP: Risk & Policy

WHAT IT DOES

What generate_diagram does on StarUML MCP Server

AI agents invoke generate_diagram to trigger actions in StarUML MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why generate_diagram needs a policy

The tool takes Mermaid code as input and executes it to generate a diagram via StarUML. This constitutes executing code/triggering external operations whose effects depend on the provided arguments. It is not purely a read or write operation — it runs Mermaid code through the StarUML application.

From the tool's definition '直接生成图表' (directly generate diagrams) using Mermaid code, implying execution of diagram-generation logic from provided code input

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

generate_diagram Rate-limited

generate_diagram stays usable, but rate-capped — a runaway agent can't fire it dozens of times 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_diagram": {
      "limits": [
        {
          "counter": "generate_diagram_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches StarUML MCP Server, so you can run agents against it safely.

FAQ

Questions about generate_diagram

What does the generate_diagram tool do? +

使用 Mermaid 代码直接生成图表。. It is categorised as a Execute tool in the StarUML MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on generate_diagram? +

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

What risk level is generate_diagram? +

generate_diagram is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit generate_diagram? +

Yes. Add a rate_limit block to the generate_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_diagram completely? +

Set action: deny in the PolicyLayer policy for generate_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_diagram? +

generate_diagram is provided by the StarUML MCP Server MCP server (stonesho/staruml_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.