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

Adds substantial behavior beyond the annotations (destructiveHint=true, idempotentHint=false): it waits up to wait_seconds then returns the VM's final state, the first boot may exceed the wait while the job continues asynchronously on Cycle, and credentials (SSH keys or generated root password) are retrievable for only ~10 minutes. This is exactly the operational nuance annotations cannot express.

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

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

Front-loads the core action and timeout behavior, then layers prerequisites and caveats — no padding in the operational sentences. The SSH/root-password login detail is useful context but slightly tangential to invoking the tool, keeping it from a perfect score.

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

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

With no output schema, the description still explains the return ('the VM's final state'), the async semantics when the wait elapses, prerequisite cluster capability, and the destructive effect of stop/restart. For a 6-parameter mutation tool with full annotation coverage, nothing an agent needs to call it correctly is missing.

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

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

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning about how wait_seconds interacts with startup: the wait may time out on first boot while the job keeps running, and 0 returns immediately per the schema. It also reinforces that action is restricted to lifecycle verbs. It does not clarify context/environment/conversation_id beyond the schema, so not a 5.

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

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

States specific verbs (start/stop/restart) and the resource (virtual machine on Cycle), which cleanly distinguishes it from siblings like cycle_control_container, cycle_control_environment, and delete_virtual_machine. An agent can identify the operation without opening the schema.

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

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

Gives real prerequisites and context: starting requires a hypervisor-capable server (verifiable via list_servers reporting 'virtualization'), and stop/restart interrupt the running guest OS. It does not explicitly name when to prefer a sibling tool (e.g., run_vm_command, reconfigure_virtual_machine), so it stops short of full routing guidance.

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