convertDiagram

THE RISK

Medium Risk

Why convertDiagram needs a policy

This tool performs format conversion—a reversible write operation that produces new file outputs (SVG, PNG, PDF) from input diagrams. It does not execute arbitrary code, delete data, or perform financial operations. While it creates new artifacts, this is a standard write-class operation.

From the tool's definition Tool description explicitly states 'Convert diagram to different formats' with support for 'SVG (PNG/PDF coming soon)'. The tool creates new output artifacts (converted diagram files) from existing diagrams without destructive modification of the original.

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

POLICY

How to control convertDiagram

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "convertDiagram": {
      "limits": [
        {
          "counter": "convertdiagram_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

convertDiagram 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.

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

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Mcp Mermiad tools

Write createCustomTemplate Create a custom template from diagram code for reuse in current session. Write generateDiagram Generate and render a Mermaid diagram to SVG file. Supports all 22+ diagram types with adv Read getDiagramInfo Analyze diagram code and return metadata (type, complexity, node/edge count, estimated ren Read getTemplate Get a specific diagram template by ID with complete code and metadata. Read listSupportedTypes List all supported Mermaid diagram types (22+ types including flowchart, sequence, class, Read listTemplates List available pre-built diagram templates (50+ templates) by category or type. Read searchTemplates Search templates by keyword (name, description, type, tags, or code content). Read validateDiagram Validate Mermaid diagram syntax and provide detailed error messages and suggestions.

All 9 Mcp Mermiad tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about convertDiagram

What does the convertDiagram tool do? +

Convert diagram to different formats. Currently supports SVG (PNG/PDF coming soon). It is categorised as a Write tool in the Mcp Mermiad MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on convertDiagram? +

Register the Mcp Mermiad MCP server in PolicyLayer and add a rule for convertDiagram: 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 Mcp Mermiad. Nothing to install.

What risk level is convertDiagram? +

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

Can I rate-limit convertDiagram? +

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

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

convertDiagram is provided by the Mcp Mermiad MCP server (narasimhaponnada/mermaid-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Mermiad tool call.

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

CHECK YOUR STACK →