vm_start
Start a virtual machine by its ID. Optionally allow memory overcommit.
This record as markdown: /tools/nasbridge/vm-start.md
What vm_start does on Nasbridge
AI agents invoke vm_start to trigger actions in Nasbridge. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why vm_start is rated High
Starting a virtual machine executes an operation that triggers external hypervisor actions and state changes. While not destructive or financial in nature, this falls under Execute because it runs a system command/operation whose effects (VM startup, resource allocation) depend on the provided ID argument.
From the tool's definition Tool name 'vm_start' and description 'Start a virtual machine by its ID' indicates execution of a VM operation. The optional 'memory overcommit' parameter shows this triggers external system operations with effects dependent on arguments.
Attacks that exploit this kind of access
The rule that runs vm_start safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Nasbridge, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For vm_start, this is the rule to start with:
vm_start stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Nasbridge, apply this rule, and every vm_start call is checked against it from then on.
Questions about vm_start
Start a virtual machine by its ID. Optionally allow memory overcommit. It is categorised as a Execute tool in the Nasbridge MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Nasbridge MCP server in PolicyLayer and add a rule for vm_start: 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 Nasbridge. Nothing to install.
vm_start is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the vm_start 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 vm_start. 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.
vm_start is provided by the Nasbridge MCP server (maverick0628/nasbridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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