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

Annotations already mark the tool as read-only, idempotent, open-world, and non-destructive, but the description adds substantial context beyond them. It discloses the eligibility rules, that non-qualifying pieces are returned with reasons, the output shape (cart link plus sample terms), and the downstream purchase/credit process.

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 front-loaded with the core action and return value, followed by qualification rules and sample terms. It is dense but mostly earns its length; the business-policy sentence about emailing order numbers is useful context but slightly expands beyond immediate invocation guidance.

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 two-parameter tool with no output schema and rich annotations, the description is complete: it covers input sources, eligibility logic, return content, handling of non-qualifying pieces, and the sample purchase/credit terms. An agent has enough information to call it correctly and explain the result.

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?

Schema description coverage is 100%, so both plan_url and variant_ids are already well documented in the input schema. The description reinforces the plan/variant alternative and the 'not both' rule but does not add significantly more meaning than the schema already provides.

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 and resource: pick qualifying sample pieces and return a cart link with one of each plus sample terms. It also defines qualification criteria ($20 or under, under 7 inches, not made-to-order), which clearly distinguishes this tool from a general cart or catalog tool.

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?

It explains that samples can come from a plan_url or from given variant_ids, and the schema reinforces that only one should be supplied. However, it does not explicitly say when to use this versus siblings like cart_link or build_plan, nor does it name when-not-to-use conditions.

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