open_drawio_mermaid

THE RISK

High Risk

Why open_drawio_mermaid needs a policy

This tool executes an external application (draw.io editor) and renders/generates a diagram from provided Mermaid.js syntax. It triggers an external operation whose effects depend on the arguments supplied, placing it in the Execute category. Misuse could render malicious or misleading diagrams, but blast radius is moderate since it primarily affects the local draw.io environment.

From the tool's definition Opens the draw.io editor with a diagram generated from Mermaid.js syntax

Documented attack patterns abuse exactly the kind of access open_drawio_mermaid gives an agent:

POLICY

How to control open_drawio_mermaid

PolicyLayer is an MCP gateway — it sits between your AI agents and Drawio Engineering, and nothing reaches the server without passing your rules. This is the rule we recommend for open_drawio_mermaid:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "open_drawio_mermaid": {
      "limits": [
        {
          "counter": "open_drawio_mermaid_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

open_drawio_mermaid 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.

Create a free account and register Drawio Engineering — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Drawio Engineering tools

Execute open_drawio_csv Opens the draw.io editor with a diagram generated from CSV data. Execute open_drawio_engineering Opens the draw.io editor with engineering diagram XML and automatically loads Write create_emc_test_setup Generates an EMC test setup cross-section diagram from a template and opens it in draw.io. Write create_pcb_stackup Generates a PCB stackup cross-section diagram and opens it in draw.io. Write create_rf_block_diagram Generates an RF signal chain block diagram from a JSON description and opens it in draw.io Write export_drawio Exports a draw.io diagram XML to an SVG or PNG file. Write markup_schematic Opens a schematic screenshot in draw.io with engineering annotations overlaid. Write open_drawio_xml Opens the draw.io editor with a diagram from XML content.

All 10 Drawio Engineering tools →

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Go deeper

High-risk tools in Drawio Engineering → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about open_drawio_mermaid

What does the open_drawio_mermaid tool do? +

Opens the draw.io editor with a diagram generated from Mermaid.js syntax. It is categorised as a Execute tool in the Drawio Engineering MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on open_drawio_mermaid? +

Register the Drawio Engineering MCP server in PolicyLayer and add a rule for open_drawio_mermaid: 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 Drawio Engineering. Nothing to install.

What risk level is open_drawio_mermaid? +

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

Can I rate-limit open_drawio_mermaid? +

Yes. Add a rate_limit block to the open_drawio_mermaid 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 open_drawio_mermaid completely? +

Set action: deny in the PolicyLayer policy for open_drawio_mermaid. 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 open_drawio_mermaid? +

open_drawio_mermaid is provided by the Drawio Engineering MCP server (rfingadam/drawio-engineering-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Drawio Engineering tool call.

Start from Drawio Engineering, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →