vmware-knight

vm_power_on

Idempotent

Power on a stopped virtual machine to enable guest tools and further management actions; returns status and is a no-op if already running.

Instructions

[WRITE] Power on a virtual machine.

Returns a status string; an already-on VM is a no-op. Reverse with vm_power_off. Call this first when a VM is off: guest tools such as vm_guest_exec only work once VMware Tools has finished booting.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "vm_name": "<vm_name>"
    },
    "name": "vm_power_on"
  }
}

Input Schema

Name	Required	Description	Default
`target`	No	Optional vCenter/ESXi target name from config. Uses default if omitted.
`vm_name`	Yes	Exact name of the virtual machine.

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.12.10Sep 23, 2026

TDQS

A4.7/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations, the description discloses that an already-on VM is a no-op, that it returns a status string, and that its effects are relevant to guest tool readiness. This adds meaningful behavioral context without contradicting the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences carry high-signal information: the operation, the no-op behavior, and the practical usage context. There is no filler or repetition, and the key verb-action is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with only two parameters, full schema coverage, and strong annotation hints, this description fully covers what an agent needs: what it does, when to call it, how it behaves on already-on VMs, and its relationship to other VM operations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage, documenting vm_name as the exact name and target as an optional config target with default behavior. The description adds no new parameter-specific details, so the schema-based baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific action and resource: "Power on a virtual machine." It also clearly distinguishes this from its reverse operation by naming vm_power_off, so an agent can identify the tool's role among many VM-related siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly says when to use this tool: "Call this first when a VM is off." It also references the relevant alternative (vm_power_off) and provides a concrete usage context by noting that guest tools depend on VMware Tools finishing boot.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server