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

With no annotations, the description carries the full burden and does well: it discloses the filter semantics (which statuses appear), the auth prerequisite ('Requires: token'), and the downstream contract (the returned `id` feeds management tools). It does not say anything about ordering or pagination, but for a small account-scoped list with no parameters that is a minor omission.

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?

Three sentences, zero waste, and the most decision-relevant information (what is included, and what to do with the results) is front-loaded. The negative rule about missing servers is placed exactly where it prevents a mistaken follow-up call.

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?

No output schema and no annotations exist, so the description must stand alone; it covers scope, exclusions, auth, and downstream usage of the returned identifier. It stops short of describing the shape of each list entry (hostname, status, plan), which an agent building a follow-up call might want, but nothing required for correct invocation 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. The description does usefully clarify that the `id` field in the response maps to the `service_id` parameter of the management tools, which is the only parameter-related meaning an agent needs here.

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 (list) and resource (the account's ACTIVE VPS services) and then enumerates the exact statuses included (active, provisioning, suspended) and excluded (deleted/cancelled). This distinguishes it cleanly from siblings like get_vps_status, which operates on a single server rather than enumerating the account's fleet.

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 tells the agent what to do with the result ('Use the `id` as `service_id` for the management tools') and gives a negative rule ('If a server is missing from this list it has been deleted — do not query its status or try to manage it'). This is genuine when-to-use/when-not-to-use guidance, not inference.

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