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

With no annotations present, the description carries the full burden and does so well: it discloses the no-auth requirement, the BYOL licensing model for Windows, RDP/port specs, the response shape (plans[], plans[].promo, meta.promotions), and detailed promo mechanics including auto-application, renewal-at-regular-price, and which plans are excluded.

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?

Purpose and usage are front-loaded and efficient, but the closing PROMO block is dense with dates, dollar figures, slugs, and edge-case exclusions that read more like marketing copy than selection guidance. It is not wasteful enough to be a 2, but it exceeds what an agent needs to choose and call the tool.

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 parameters, the description compensates by explaining the returned structure (plans[], plan_id for monthly/annual, promo fields, meta.promotions). Nothing an agent needs to invoke and interpret the tool 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?

The tool takes zero parameters, so the baseline is 4 and there is nothing to disambiguate. The description correctly adds no parameter guidance because none is needed.

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 and resource ('List all available VPS plans (catalog) with pricing, specs and the OS images') and enumerates the two plan families (Linux NAT/dedicated IPv4, Windows Server 2022 BYOL). It is immediately distinguishable from siblings like list_vps (instances) and order_vps (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?

Explicitly says 'Use this first to pick a `product` slug and an `os_id` for `order_vps`', naming the downstream tool and the reason to call this one first. It also states 'No authentication needed' / 'Requires: nothing', removing ambiguity about prerequisites.

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