vmware-knight

cluster_add_host

Move an existing vCenter-managed ESXi host into a target cluster. Returns success if already a member, or an error if the host is not found.

Instructions

[WRITE] Move an ESXi host that vCenter already manages into a cluster.

The host must already be in vCenter inventory (standalone or in another cluster) — this does NOT register brand-new hosts and takes no host credentials; use the vCenter UI for first-time registration. Idempotent: a host already in the cluster returns success without change. Maintenance mode is not required to join (it IS required by cluster_remove_host). Check membership first with cluster_info. Returns a status string: moved, already-in-cluster, or a not-found error.

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": {
      "cluster_name": "<cluster_name>",
      "host_name": "<host_name>"
    },
    "name": "cluster_add_host"
  }
}

Input Schema

Name	Required	Description
`target`	No	vCenter target from config.yaml; omit for the default target.
`host_name`	Yes	Host name as shown in vCenter inventory, usually the FQDN, e.g. "esxi-01.lab.local".
`cluster_name`	Yes	Destination cluster (create with cluster_create).

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.12.10Sep 23, 2026

TDQS

A3.8/5.0

Behavior1/5

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

The description explicitly states 'Idempotent: a host already in the cluster returns success without change,' but the annotations declare idempotentHint=false. This is a direct contradiction, so despite adding otherwise useful behavioral context, this dimension must score the lowest.

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

Conciseness4/5

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

The description is front-loaded with '[WRITE]' and a clear one-line purpose. Each subsequent sentence adds distinct value, though it is longer than strictly necessary; the structure is logical and scannable.

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?

Given output schema exists and parameter coverage is complete, the description covers prerequisites, idempotency, maintenance-mode expectations, a recommended pre-check, and the return status values. An agent has enough context to invoke the tool correctly.

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?

Schema description coverage is 100%, so the baseline is 3. The description adds helpful context like 'takes no host credentials' and that cluster_name references a cluster created via cluster_create, but it does not substantially expand parameter meaning beyond the schema.

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 opens with a specific verb and resource: 'Move an ESXi host that vCenter already manages into a cluster.' It clearly scopes the operation to already-managed hosts and distinguishes this tool from registration workflows and from cluster_remove_host.

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?

It gives explicit when-to-use and when-not-to-use guidance: no brand-new host registration, no host credentials, use the vCenter UI for first-time registration. It also references cluster_info as a precursor and contrasts maintenance-mode requirements with cluster_remove_host.

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

Deploy Server