Generate and render a Mermaid diagram to SVG file. Supports all 22+ diagram types with advanced layout options.
AI agents use generateDiagram to create or update resources in Mcp Mermiad — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Mermiad environment.
This tool creates new diagram files in SVG format. It is a Write operation because it produces new data artifacts (SVG output). There is no indication it modifies, deletes, or overwrites existing data irreversibly. The blast radius is low—misuse would at worst create unwanted diagram files, with no financial, security, or destructive impact. No code execution or external command invocation is evident.
From the tool's definition Tool generates and renders a Mermaid diagram to SVG file. The verb 'generate and render' combined with 'to SVG file' indicates file creation or modification. The description does not indicate deletion, overwriting of existing files, or destructive operations.
Documented attack patterns abuse exactly the kind of access generateDiagram gives an agent:
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 generateDiagram:
{
"version": "1",
"default": "deny",
"tools": {
"generateDiagram": {
"limits": [
{
"counter": "generatediagram_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}generateDiagram 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.
Free to start. No card required.
Generate and render a Mermaid diagram to SVG file. Supports all 22+ diagram types with advanced layout options. 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.
Register the Mcp Mermiad MCP server in PolicyLayer and add a rule for generateDiagram: 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.
generateDiagram is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the generateDiagram 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.
Set action: deny in the PolicyLayer policy for generateDiagram. 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.
generateDiagram 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.
Start from Mcp Mermiad, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
9 Mcp Mermiad tools catalogued and risk-classified — across an index of 43,000+ MCP servers.