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

Annotations already cover read-only, idempotent, non-destructive, and closed-world behavior, so the description adds useful context by listing the returned offer and purchase fields. It does not describe rate limits, auth requirements, or how missing api_pass changes behavior, but the annotation coverage lowers that burden.

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 purpose is front-loaded in one compact sentence, and the long return-field list is dense but justified because there is no output schema. The description is not bloated, though the return object could be formatted more readably.

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 one-parameter, read-only tool with rich annotations and no output schema, the description provides enough return-shape information for an agent to understand the result. The main missing piece is an explicit mapping of api_pass presence to discovery versus private-purchase inspection.

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 single optional api_pass parameter is fully documented in the schema, including its private pass format and the warning to save it before buying. The description only hints at it via 'inspect a private purchase' and adds no format or behavior details beyond the schema, so baseline 3 is appropriate.

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 two concrete functions: discovering the monthly data package and inspecting a private purchase. This is clearer than a tautology and gives the agent a usable verb/resource pairing, though it does not explicitly differentiate itself from the sibling api_access_buy.

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 two modes imply when the tool is useful, but the description never explicitly says to call it without api_pass for discovery versus with api_pass for inspection. It also does not mention when to use api_access_buy instead, so usage is only implied.

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