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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so safety is covered. The description adds useful non-annotation behavior: the call is 'Free' and returns a comprehensive price-list payload. It doesn't discuss rate limits or response shape, but with annotations the bar is lower.

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 price list:' and then a compact enumeration of returned data, followed by a single usage directive and cost note. No sentence feels wasted.

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 zero-parameter, read-only tool with no output schema, the description fully covers what the agent will get back and when to call it. Annotations handle the safety profile, leaving nothing critical 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 has zero parameters, so the baseline is 4. The description correctly doesn't invent parameter details and instead focuses on the returned content.

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?

Opens with a precise naming of the resource ('The price list') and enumerates exactly what it returns: credits per call class, PAYG bands, plan pricing, included credits, and payment methods. This clearly distinguishes it from sibling tools like subscribe_plan, get_payment_options, and get_usage.

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?

Gives explicit usage guidance: 'Use it before subscribe_plan,' which tells the agent both when and why to call it. It lacks an explicit 'when not to use' or mention of alternative pricing-related siblings, but the context is clear.

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