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

Annotations already cover readOnlyHint and openWorldHint, so the description goes beyond them usefully: no-auth access, flat catalog scope, BYOL licensing semantics for Windows, and that automatic offers surface in `plans[].promo` and `meta.promotions`. It stops short of describing pagination or whether plan availability is regional, but the safety/behavior profile is well covered.

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 resource and scope, then prerequisites and usage. The price points and port speed are mildly decorative but arguably help an agent sanity-check catalog expectations; still, it's a dense single block rather than tightly structured.

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 carries return-shape duty and does so (`plans[]`, `plan_id` cadence, `promo`, `meta.promotions`). Combined with zero parameters and annotations covering the safety profile, an agent has everything needed to call it and interpret the result.

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?

The tool takes zero parameters, so there is nothing to disambiguate and the baseline is 4. The description instead documents the response shape (`plans[]` with monthly and annual `plan_id`, `promo`, `meta.promotions`), which is bonus value rather than parameter guidance.

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?

Specific verb + resource (list the VPS plan catalog), explicitly scoped to pricing, specs and bootable OS images, with the two catalog segments (Linux NAT/dedicated, Windows BYOL) called out. That 'catalog vs. existing instances' framing separates it from list_vps without needing to open either 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?

States the exact next action — 'Use this first to pick a `product` slug and an `os_id` for `order_vps`' — which routes the agent to the correct follow-up tool. It also declares prerequisites ('Requires: nothing', 'No authentication needed'), removing any need for a login-then-list inference.

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