create_from_mermaid · Excalidraw MCP Server MCP

WHAT IT DOES

What create_from_mermaid does on Excalidraw MCP Server

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

WHY IT NEEDS A POLICY

Why create_from_mermaid needs a policy

This tool creates and renders new diagram elements on a live Excalidraw canvas. This is a reversible Write operation - elements can be deleted or modified afterward. It does not execute arbitrary code, delete data irreversibly, move money, or retrieve without side effects.

From the tool's definition Tool performs 'Convert a Mermaid diagram to Excalidraw elements and render them on the canvas' - creates new elements on the canvas via programmatic conversion, aligning with Write operations (create).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_from_mermaid Rate-limited

create_from_mermaid 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_from_mermaid": {
      "limits": [
        {
          "counter": "create_from_mermaid_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 Excalidraw MCP Server, so you can run agents against it safely.

FAQ

Questions about create_from_mermaid

What does the create_from_mermaid tool do? +

Convert a Mermaid diagram to Excalidraw elements and render them on the canvas. It is categorised as a Write tool in the Excalidraw 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 create_from_mermaid? +

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

What risk level is create_from_mermaid? +

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

Can I rate-limit create_from_mermaid? +

Yes. Add a rate_limit block to the create_from_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 create_from_mermaid completely? +

Set action: deny in the PolicyLayer policy for create_from_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 create_from_mermaid? +

create_from_mermaid is provided by the Excalidraw MCP Server MCP server (kakacoding1/mcp_excalidraw). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.