List all variables
AI agents call variable_list to retrieve information from N8n Fabric without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves/queries data (n8n workflow variables) without side effects. It matches the Read category definition: 'retrieves or queries data; no side effects (search, list, get, fetch).' The 'list' action is explicitly mentioned as a Read-category example.
From the tool's definition Tool name is 'variable_list' and description states 'List all variables' — a pure retrieval operation with no modification, deletion, or execution capability.
Attacks that exploit this kind of access
List all variables. It is categorised as a Read tool in the N8n Fabric MCP Server, which means it retrieves data without modifying state.
Register the N8n Fabric MCP server in PolicyLayer and add a rule for variable_list: 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 N8n Fabric. Nothing to install.
variable_list 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 variable_list 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 variable_list. 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.
variable_list is provided by the N8n Fabric MCP server (ry-ops/n8n-fabric). 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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