Loading ToolBench
Enterprise-grade Model Context Protocol (MCP) server for comprehensive VMware vCenter Server management
This server has 6 tools with basic schemas and descriptions, but falls short of production quality in several key areas. All tools have descriptions (positive), but most descriptions are too brief (10-30 chars) to guide LLM decision-making. Parameter descriptions exist but are generic and lack actionable constraints. No output schemas are documented, forcing agents to guess what fields to expect. No error handling guidance, recovery paths, or input validation messaging is evident. The schemas provided are minimal JSON Schema declarations without range constraints, enums for restricted values, or dependency relationships. This server scores in the D range (50-59 fair/poor), typical of community STDIO implementations.
Create a new cluster
Create a new datacenter in vCenter
Create a new virtual machine
List all clusters
List all datacenters
List virtual machines
Descriptions too brief across all 6 tools (range 20-34 chars vs 50-200 baseline). Descriptions are critical for LLM tool selection, too short provides no context on WHEN to use the tool, what it RETURNS, or SIDE EFFECTS. This violates pattern:tool-description and increases hallucination risk.
No output schemas documented for any tool. Agents cannot know what fields to expect from responses (e.g., does list_vms return vm_id, vm_name, power_state, or all three?). This forces agents to make incorrect assumptions and breaks tool chaining (e.g., an agent cannot pass create_vm's output to a downstream tool if it does not know the field names).
Inferred effective spec: <=2025-11-25.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-22 | F | 47 | <=2025-11-25 | v2 |
| 2026-03-09 | F | 0 | - | v1 |
Enum constraints missing for restricted-choice parameters (power_state, guest_os). LLMs will hallucinate invalid values. Example: power_state lacks enum like ['powered-on', 'powered-off', 'suspended']; guest_os lacks enum like ['windows-server-2019', 'ubuntu-20.04', 'rhel7']. This violates pattern:constrained-input.
No error handling guidance or recovery paths. If a user passes an invalid datacenter name to create_cluster, the tool will fail silently (500 error, stack trace). The description should say: 'If datacenter not found, try list_datacenters() first.' This enables agent self-correction per pattern:recovery-guide.
No pagination or result limit hints for list_* tools. Agents do not know if list_datacenters returns 5 items or 5000. Without pagination parameters (limit, offset, cursor) or a stated max result cap, agents risk exhausting context windows or missing results. This violates pattern:paginated-result.
Destructive operations (create_datacenter, create_cluster, create_vm) lack confirmation or dry-run patterns. Agents can create resources with no safeguard against mistakes. Per pattern:confirmation-request, irreversible operations should require explicit user confirmation or a dry-run step to prevent catastrophic errors.
Parameter ambiguities and missing validation hints. Examples: 'folder' parameter in create_datacenter does not specify format (e.g., '/root/folder-name' or just 'folder-name'?); 'datacenter' parameter in create_cluster does not clarify whether it accepts name or ID; 'cluster' parameter in list_vms lacks clarity on valid format. Descriptions should state: 'datacenter: name of the parent datacenter (string, case-sensitive, required)'.
No indication of boolean parameter defaults for create_cluster (drs_enabled, ha_enabled, vsan_enabled). LLMs will not know whether omitting these parameters enables or disables the features. This breaks idempotency and causes unpredictable side effects. Defaults must be stated or explicitly required.