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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It states it lists plans with prices, but it does not clarify how the optional parameters (type, location) affect the output, whether it returns all plans when no filter is given, or what the response structure looks like. The availability constraints are useful, but the description leaves significant ambiguity about the tool's actual 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 two sentences with no wasted words. The core action is front-loaded, and the availability constraints are presented as a supplementary note. It is well-structured for an agent to quickly parse the tool's primary function and key restrictions.

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?

Given the tool has optional parameters and no output schema, the description should clarify how the agent should invoke it. It does not mention that type and location are filters, nor what happens if they are omitted (e.g., returns all plans across all locations). It also does not specify what fields the response will contain beyond 'prices', leaving the agent uncertain about the returned data. This is a notable gap for a simple list tool.

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?

Although the schema already documents both parameters with 100% coverage, the description adds meaningful context beyond the schema by linking plan types to location availability (e.g., GPU is unavailable in Russia due to export controls). This helps an agent understand the semantic constraints of the 'type' parameter in combination with 'location', which the schema alone does not convey.

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 states a specific verb ('List'), a clear resource ('plans'), and enumerates the plan types (VPS, dedicated, RDP, GPU) along with the key detail that prices are per location. It distinguishes itself from the sibling list_locations by explicitly mentioning plans, making the purpose unambiguous.

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 provides availability constraints (RDP only in NL/RO/MD/RU, GPU only in IS/NL/RO/MD) that hint at when this tool would be appropriate for querying specific plan types, but it does not explicitly state when to use this tool versus alternatives or when not to use it. No sibling tool is mentioned, so guidance is implied rather than explicit.

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