AI agents call preview_nat_rule to retrieve information from AF_MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The 'preview' prefix strongly suggests this tool retrieves or displays a NAT rule without applying changes. However, the empty description lowers confidence. Given the sibling tool 'apply_nat_rule' exists as a separate action, 'preview' is likely a read operation that shows what would be changed. Severity is medium because NAT rule information on security devices is sensitive even if only read.
From the tool's definition Tool name 'preview_nat_rule' suggests a read/preview operation; description is empty and uninformative.
Attacks that exploit this kind of access
preview_nat_rule. It is categorised as a Read tool in the AF_MCP MCP Server, which means it retrieves data without modifying state.
Register the AF_ MCP server in PolicyLayer and add a rule for preview_nat_rule: 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 AF_MCP. Nothing to install.
preview_nat_rule 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 preview_nat_rule 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 preview_nat_rule. 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.
preview_nat_rule is provided by the AF_ MCP server (xiaqijun/af_mcp). 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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