Purchase VPS

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

With no annotations provided, the description must disclose behavioral traits, but it only says 'Purchase a new virtual machine.' It does not mention that this will likely initiate a billing transaction, provision a server, or return an order ID. Missing details about side effects, required permissions, or asynchronous behavior.

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 a single, clear sentence with no filler or redundant information. It is extremely concise and front-loaded, achieving the goal of being short and readable.

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?

The tool has no output schema, no annotations, and only a minimal description. Given the complexity of purchasing a VPS (needing catalog item selection, payment method validation, and potential provisioning steps), the description is incomplete. It does not mention any return values, post-purchase actions, or how to obtain the required IDs.

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 100%, so baseline is 3. The description adds no additional meaning to the parameters beyond what the schema already provides (item_id and payment_method_id). However, since the schema is fully documented, the description does not need to compensate.

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 clearly states the action ('Purchase') and the resource ('a new virtual machine'). It is specific enough to distinguish from most siblings, though it could better differentiate from similar purchase tools like billing_create_order or domains_purchase.

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?

No guidance is provided on when to use this tool versus alternatives such as billing_create_order or vps_setup. The description does not mention any prerequisites (e.g., retrieving available VPS plans via billing_get_catalog or ensuring a payment method exists).

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