render_mermaid_file · Vaults Diagram Tools MCP

WHAT IT DOES

What render_mermaid_file does on Vaults Diagram Tools

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

WHY IT NEEDS A POLICY

Why render_mermaid_file needs a policy

An AI agent can call render_mermaid_file faster than any human can review — one bad instruction and it creates or modifies resources in Vaults Diagram Tools by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

render_mermaid_file Rate-limited

render_mermaid_file 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_mermaid_file": {
      "limits": [
        {
          "counter": "render_mermaid_file_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about render_mermaid_file

What does the render_mermaid_file tool do? +

Render a .mmd/.mermaid file or tree to SVG/JPEG and optional PNG/ASCII artifacts. It is categorised as a Write tool in the Vaults Diagram Tools 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_mermaid_file? +

Register the Vaults Diagram Tools MCP server in PolicyLayer and add a rule for render_mermaid_file: 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 Vaults Diagram Tools. Nothing to install.

What risk level is render_mermaid_file? +

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

Can I rate-limit render_mermaid_file? +

Yes. Add a rate_limit block to the render_mermaid_file 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_mermaid_file completely? +

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

render_mermaid_file is provided by the Vaults Diagram Tools MCP server (vaults-diagram-tools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.