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

The description adds significant behavioral context beyond annotations: it clarifies that payment occurs on Stripe's secure page, the agent never handles card details, and credits are added post-payment. This fully compensates for the absence of detailed 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 concise and well-structured, front-loading the core purpose. It could be slightly shortened by merging sentences, but each sentence contributes essential information.

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?

Given the tool's complexity (payment flow with external redirect), the description covers all critical aspects: what it does, how payment works, the credit pack value, and its relation to promote_listing. No output schema exists, but the return value is clearly described.

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 schema already provides full coverage for the single parameter 'locale' with enum values and description. The description does not add further semantics beyond naming the parameter, so a baseline score of 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 clearly states the tool starts a purchase of a promotional-credit pack, returns a Stripe checkout link, and explains the pack details (5 credits, each promotes for ~14 days). It distinctively separates from sibling tools like promote_listing which spends credits.

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 explains when to use (to buy credits for promotion) and implicitly suggests not to use promote_listing until credits are purchased. However, it lacks explicit exclusion statements or alternative guidance for members who already have credits.

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