purchase_volume

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

The description goes well beyond the annotations by disclosing that the operation spends real money, checks balance and quota, requires explicit confirmation, behaves asynchronously by returning a task_id, and has region-dependent behavior with a notable error message. This gives the agent important expectations that annotations do not convey.

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?

The description is dense but relevant, covering purpose, cost, confirmation, kind semantics, regional caveats, and asynchronous behavior without wasted sentences. The parenthetical about the API's error message is slightly verbose but still useful. It is appropriately sized for the complexity of the operation.

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?

For a tool with no output schema and sparse annotations, the description provides a strong operational picture: it states return behavior, follow-up polling steps, and the key constraints. The main completeness gap is the lack of guidance for required parameters pop and size_gb, which an agent would need to invoke the tool 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 description coverage is 0%, so the description carries the burden. It adds meaning for kind (data vs boot), confirm (real money), and vps_id (pinning in unsupported regions), but it does not explain the required pop or size_gb parameters, which remain ambiguous. Partial compensation, but with clear gaps.

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?

The description opens with a specific verb and resource: 'Purchase a new standalone volume.' It also distinguishes itself from related volume operations by explaining that a boot volume is for a future VPS and is 'not attached to anything existing,' which differentiates it from attach_volume and related operations.

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?

The description gives strong context for when to use the tool, including the confirm=true requirement, the difference between data and boot volumes, and the region-specific rule requiring vps_id for data volumes where fleet-volume support is absent. It does not explicitly name alternative sibling tools, but the operational guidance makes the intended usage clear.

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