AI agents call tunnel.list to retrieve information from Ngsrv without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns tunnel metadata from the current session without creating, modifying, deleting, or executing operations. It is purely informational and read-only, making it the least risky category.
From the tool's definition Tool name 'tunnel.list' and description 'List HTTPS tunnels started by this MCP process in the current session' indicate retrieval of tunnel status information with no modification or side effects.
Attacks that exploit this kind of access
List HTTPS tunnels started by this MCP process in the current session. It is categorised as a Read tool in the Ngsrv MCP Server, which means it retrieves data without modifying state.
Register the Ngsrv MCP server in PolicyLayer and add a rule for tunnel.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 Ngsrv. Nothing to install.
tunnel.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 tunnel.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 tunnel.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.
tunnel.list is provided by the Ngsrv MCP server (ngsrv/ngsrv-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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