Display a Mermaid flowchart in a visual drag-and-drop editor. Opens a browser-based editor where the user can visually edit the diagram. Call get_diagram_feedback() afterwards to retrieve the user
AI agents invoke show_diagram to trigger actions in Software Design Mermaid. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
The tool triggers an external operation by opening a browser-based editor, which constitutes executing an action in an external environment. It's not purely reading data nor just writing/modifying stored data — it actively launches a browser application and renders an interactive UI, making Execute the most appropriate category.
From the tool's definition Opens a browser-based editor where the user can visually edit the diagram
Documented attack patterns abuse exactly the kind of access show_diagram gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Software Design Mermaid, and nothing reaches the server without passing your rules. This is the rule we recommend for show_diagram:
{
"version": "1",
"default": "deny",
"tools": {
"show_diagram": {
"limits": [
{
"counter": "show_diagram_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}show_diagram 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.
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Display a Mermaid flowchart in a visual drag-and-drop editor. Opens a browser-based editor where the user can visually edit the diagram. Call get_diagram_feedback() afterwards to retrieve the user. It is categorised as a Execute tool in the Software Design Mermaid MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Software Design Mermaid MCP server in PolicyLayer and add a rule for show_diagram: 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 Software Design Mermaid. Nothing to install.
show_diagram is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the show_diagram 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 show_diagram. 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.
show_diagram is provided by the Software Design Mermaid MCP server (wzh4464/software-design-mermaid-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Software Design Mermaid, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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3 Software Design Mermaid tools catalogued and risk-classified — across an index of 43,000+ MCP servers.