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

With no annotations present, the description carries the full behavioral burden and does disclose two real traits: cost ('Free') and safety ('no side effects'), which effectively communicate the read-only profile. It also discloses the payment-rule content (USDT TRC20, exact amount). It stops short of covering rate limits or whether catalog data can change between calls.

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?

Two short sentences with zero filler; the resource list is front-loaded and the safety/cost qualifier follows. Every clause earns its place.

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?

For a no-arg tool with no output schema, the description enumerates the returned content (plans, prices, payment rules) and flags it as free and side-effect free, which is enough for an agent to call it correctly. It does not describe result shape or ordering, a minor gap given no output schema exists to cover it.

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 and the schema coverage is 100%, so there is nothing for the description to clarify. Baseline 4 applies for a no-parameter tool.

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 ('Portvan plans, prices and payment rules'), so an agent immediately knows this is the read/catalog entry point. It does not explicitly name the siblings portvan_create_order or portvan_order_status, but the read-only listing framing makes the distinction inferable.

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?

There is no explicit when-to-use or when-not-to-use statement, and no alternatives are named. The 'Free, no side effects' note implies it is safe to call at any time, and a catalog is naturally the prerequisite for creating an order, but this routing logic is left to inference.

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