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

Annotations already establish readOnlyHint and destructiveHint, so the description correctly does not repeat those. It adds a meaningful behavioral guarantee: the endpoint deliberately withholds paid result content, and the 'FREE STATUS' prefix signals the status lookup is free. This goes beyond the structured annotations.

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 a single efficient sentence with the key qualifier 'FREE STATUS' front-loaded. No words are wasted, and the most important behavioral distinction is stated up front.

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 simple one-parameter, read-only status tool with annotations covering safety, the description provides the essential invocation details: what is returned, how the purchase is identified, and what is intentionally omitted. It is slightly light on possible status values or error behavior, but the tool's simplicity keeps this gap minor.

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?

With 0% schema description coverage, the description must compensate. It confirms that the sole parameter is an idempotency key used to identify the purchase, which adds a small amount of semantic context beyond the raw property name. However, it does not explain constraints, uniqueness expectations, or how a caller obtains a valid key.

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 uses a specific verb ('Returns') and resource ('state of a machine-commerce purchase'), and identifies the lookup mechanism ('by its idempotency key'). The phrase 'without revealing paid result content' differentiates this status tool from content-returning purchase endpoints.

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 implies when to use this tool: when you need purchase state without paid content. However, it does not explicitly name alternatives or provide exclusions, despite sibling tools like fulfillment.status and get_fulfillment_status existing.

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