Render a mingrammer/diagrams Python snippet to PNG and return the image. The code must be a complete Python script using from diagrams import ... imports and a with Diagram(...) context manager block. Use search_nodes to verify node names and get correct import paths before writing code. Read the...
Risk signalsAccepts freeform code/query input (code) · Accepts file system path (filename)
Part of the Diagrams MCP server.
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AI agents use render_diagram to create or modify resources in Diagrams MCP. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call render_diagram repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Diagrams MCP.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"render_diagram": {
"limits": [
{
"counter": "render_diagram_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Diagrams MCP policy for all 9 tools.
These attack patterns abuse exactly the kind of access render_diagram gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Render a mingrammer/diagrams Python snippet to PNG and return the image. The code must be a complete Python script using from diagrams import ... imports and a with Diagram(...) context manager block. Use search_nodes to verify node names and get correct import paths before writing code. Read the diagrams://reference/diagram, diagrams://reference/edge, and diagrams://reference/cluster resources for constructor options and usage examples. Args: code: Full Python code using the diagrams library. filename: Output filename without extension. format: Output format — "png" (default), "svg", or "pdf". download_link: If True, return a temporary download URL path (/images/{token}) that expires after 15 minutes; if False, return inline image bytes. Defaults to True (URL) — set DIAGRAMS_INLINE_DEFAULT=true on the server to flip the default. SVG/PDF and PNGs larger than the inline limit always use a download link.. It is categorised as a Write tool in the Diagrams MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Diagrams MCP server in PolicyLayer and add a rule for render_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 Diagrams MCP. Nothing to install.
render_diagram 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 render_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 render_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.
render_diagram is provided by the Diagrams MCP server (pypi:diagrams-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 9 Diagrams MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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