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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, covering the safety profile. The description adds genuine non-annotation context: the tool is free, packages are one-off, and nothing is metered or subscribed. It does not describe freshness, pagination, or any failure behavior, so it adds some but not rich value.

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?

It is front-loaded with the most useful fact ('Free') and the catalogue contents are enumerated efficiently. However, the closing sentence ('The per-call doors stay open beside them') is vague, decorative prose that costs space without adding actionable meaning.

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, the description carries the burden of explaining returns and does so reasonably: 11 products, 13 prices in AUD, the per-SKU payment unit, package output, and input destination. It is complete enough for an agent to know what it will get, though the enumeration is impressionistic rather than exact.

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, which is the baseline-4 case. Nothing in the schema needs compensating for, and the description correctly implies no input is required.

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 identifies a specific resource (the one-off card packages) and characterizes the output as a machine-readable catalogue of products, prices, SKUs, returns, and input destination. It implicitly contrasts with the per-call alternative ('The per-call doors stay open beside them'), which helps distinguish it from buy_card_package, though it never names the sibling directly.

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?

Usage is only implied: the word 'catalogue' and 'Free' suggest a discovery step, and the note about per-call doors hints that other paths exist. There is no explicit 'use this before buying a package' instruction or named alternative, so the agent must infer when to reach for this tool over buy_card_package.

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