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

No annotations are provided, so the description carries full burden, and it delivers: one reboot (~1 min), immediate prorated charge from prepaid balance, 402 with needed/balance shortfall, refund of unused difference for convert_to_nat, and new renewal price. This is exactly the side-effect disclosure a mutation tool needs.

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-loaded with the core action and its side effects, and nearly every sentence carries operational value (reboot, charge, errors). The closing 'Requires: token + balance + confirm: true' partially restates earlier content, which is the only waste.

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 and no annotations, the description still covers prerequisites, mutation semantics, error codes and recovery, and downstream billing effects. An agent has everything needed to invoke this correctly.

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 already 100%, so baseline is 3, but the description adds provenance for target_plan ('product_id from get_upgrade_options') and reinforces that confirm must be true. Minor confusion: it references 'convert_to_nat' as if it were an input, though it is not a parameter of this schema.

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 a specific verb+resource with scope: 'Switch a VPS to another plan IN PLACE — files and the OS are kept'. It distinguishes it from get_upgrade_options (which only lists options) and makes clear this is the mutation counterpart.

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?

Explicitly routes the agent: target_plan comes from get_upgrade_options, and a 422 means 'not an upgrade (pick from get_upgrade_options)'. It also prescribes the recovery path for 402 (top up and retry), so usage conditions are fully covered.

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