AI agents call get_diagram to retrieve information from Mermaid without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
diagramType | string | Yes |
Parameters from the server's own tool schema.
This tool queries and retrieves diagram objects without side effects. It is a read-only operation that does not create, execute, delete, or modify data. The low severity reflects minimal risk from misuse—an AI agent could retrieve diagrams but cannot cause harm through retrieval alone.
From the tool's definition Tool name 'get_diagram' and description 'get diagram of a type' indicate retrieval of existing diagram data with no modification. The instruction to use 'get_diagram_examples' for creation further confirms this retrieves rather than creates content.
Attacks that exploit this kind of access
get diagram of a type, if want to create a diagram, must use the get_diagram_examples tool to see examples. It is categorised as a Read tool in the Mermaid MCP Server, which means it retrieves data without modifying state.
get_diagram accepts 1 parameter: diagramType. Required: diagramType. The full parameter table on this page comes from the server's own tool schema.
Register the Mermaid MCP server in PolicyLayer and add a rule for get_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 Mermaid. Nothing to install.
get_diagram is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_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 get_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.
get_diagram is provided by the Mermaid MCP server (mermaid-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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