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MCP server for managing VMware vSphere infrastructure including virtual machines, hosts, datacenters, networks, datastores, and advanced operations like VM cloning
This server has fundamental definition quality issues that prevent confident production use. All 8 tools are explicitly registered with @mcp.tool() decorators and have basic descriptions, but critical gaps exist: (1) No input schema validation is visible, parameters are defined as function arguments but lack formal JSON Schema constraints (type, enum, minLength, pattern, etc.); (2) descriptions are present but generic and under-optimized for LLM decision-making (e.g., 'List all virtual machines with basic information' lacks WHEN to use this vs. get_vm_details or context about return fields); (3) output schemas are completely undocumented, callers cannot predict what fields to expect, forcing LLMs to parse unstructured string responses; (4) error handling is present but not granular, all exceptions are caught and coerced to strings, making it impossible for agents to distinguish retryable (connection timeout) from non-retryable (auth failed) failures; (5) security practice is acceptable (no secrets in params, environment-based injection), but audit logging is absent. The server scores highest on basic naming (verb_noun pattern is consistent) but fails on parameter rigor and output documentation.
Get detailed information about a datacenter.
Get detailed information about an ESXi host.
Get detailed information about a specific virtual machine.
List all datacenters.
List all ESXi hosts.
List all virtual machines with basic information.
Power off a virtual machine.
No formal JSON Schema validation for tool inputs. Parameters are declared as Python function arguments (hostname: str, vm_id: str) but no JSON Schema with type, enum, minLength, pattern, or default constraints is visible in FastMCP registration. LLMs cannot verify valid inputs before calling and cannot understand constraints like 'vm_id must start with vm- or be a VM name' without explicit schema documentation.
Output schemas are completely undocumented. All tools return string responses with unstructured text output (e.g., 'Found 3 VMs\n• VM1 (ID: vm-123)\n...'). LLMs cannot predict return fields, must parse plain text, and cannot extract structured data for downstream tool chaining. No documentation of what fields callers should expect.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-22 | F | 39 | 2026-07-28+ | v2 |
| 2026-03-09 | F | 13 | - | v1 |
Power on a virtual machine.
Descriptions lack actionable context for LLM selection. E.g., 'List all virtual machines with basic information' does not explain WHEN to use this vs. get_vm_details, what 'basic information' includes, whether results are paginated, or what fields are returned. Descriptions should be 50-200 chars and answer: What does it do? When use it? What does it return?
Power tools (power_on_vm, power_off_vm) lack confirmation or dry-run support. These are destructive operations (state changes) that agents can invoke accidentally. No confirmation step, no dry-run preview, and no recovery guidance if an error occurs mid-operation.
Error handling is not categorized for agent recovery. All exceptions are caught and converted to generic strings via _handle_error(). LLMs cannot distinguish retryable errors (timeout, connection) from user-fixable (bad hostname) from fatal (auth failed). No error classification guide tells agents what to do next.
List tools (list_vms, list_hosts, list_datacenters) have no pagination parameters. No limit, offset, page_size, or cursor support visible. If a vCenter has 1000s of VMs, responses will be huge, blow context windows, and fail. Results should be capped at 20-50 with pagination offered.
Parameter descriptions are minimal or missing constraints. E.g., 'vm_id: Virtual machine ID or name' does not clarify format (does 'vm-' prefix matter? case-sensitive?), valid range, or examples. Parameter descriptions should include format, range, and enum constraints directly.
No audit logging or request tracing. Agent calls are not logged with timestamp, caller, parameters, result, or outcome. Compliance, debugging, and incident response are blind, no way to trace who invoked what tool, when, or with what effect.
Tool annotations (readOnlyHint, destructiveHint, idempotentHint) are not declared. power_on_vm and power_off_vm should be marked destructive. list_* tools should be marked read-only. These annotations help LLMs reason about safety and retry logic.