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

It adds the concrete requirement for a JWT or an rk_ key, which is useful context absent from the annotations. Beyond that, it provides little operational detail and does not explicitly clarify side-effect behavior even though readOnlyHint is false, though there is no direct contradiction.

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?

Two compact fragments front-load authentication and then enumerate exactly what is included. The field-name hints add precision without filler or repetition.

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-argument tool with an output schema, the credential requirement, resource scope, and key field hints are nearly sufficient for correct selection and invocation. Explicit sibling differentiation and clearer read behavior would make it more complete.

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?

There are no parameters, so no input documentation is needed and the zero-parameter baseline applies. The period_end and runs_left parentheticals usefully clarify returned concepts rather than inputs.

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 the resource as the caller’s paid unlocks, passes, and run packs, making the purchase-inventory purpose clear despite the lack of an explicit retrieval verb. It does not distinguish this view from subscription_status or free_tier_status.

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 authentication prerequisite and resource scope imply using the tool to inspect one’s own purchases, but there is no explicit when-to-use statement. It also does not explain when a sibling such as subscription_status or free_tier_status would be more appropriate.

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