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

With no annotations, the description carries the transparency burden and does meaningful work: it reveals that prices are final, no VAT/tax is added at checkout, and the tool also reports a free allowance. These are non-obvious behavioral details beyond a bare 'list packs' statement, even if it doesn't explicitly declare read-only status or auth requirements.

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 three sentences with no filler: the first defines what is returned, the second gives the call-before-create_checkout workflow, and the third adds essential pricing and free-trial context. Each sentence earns its place and the primary action is front-loaded.

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-parameter, no-output-schema read-only listing tool, the description provides everything an agent needs to invoke and use it correctly: return fields, call timing relative to create_checkout, pricing finality, and the free allowance. Nothing material 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 has zero parameters and an empty input schema, so there is nothing for the agent to misunderstand. Per baseline for zero-parameter tools, the description needs no parameter-level detail, and the fields it lists instead describe the return content usefully.

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 opens with a specific verb and resource: 'Return every smack pack for sale,' then enumerates the exact fields returned (id, price in USD, smack count, bonus). It also plants a clear differentiation hook by naming create_checkout as the downstream tool, so an agent can distinguish this from purchase and account tools.

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 explicitly says to call this before create_checkout and explains the purpose: to inform the person what they are about to pay. This gives clear, concrete usage context, though it does not spell out when-not-to-use it or name alternative list-like tools.

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