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

The description goes well beyond the annotations by disclosing that the token is single-use, stripped amount-capped, prices are fixed server-side, and units become usable immediately on success. It also clearly states the cost implications: charges the user's approved payment method and consumes no AI credits. No contradiction with annotations exists.

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 dense but every sentence earns its place. It front-loads the core action and token requirement, then gives product details, safety rules, fallback behavior, and side effects in a logical order. The repeated warnings are justified given the financial risk.

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 payment-triggering tool with an output schema available, the description is complete: it covers preconditions, product semantics, fallback routing when the tool cannot be used, postcondition behavior, and cost implications. Nothing critical is missing for an agent to decide whether and how to call it.

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 documents 75% of the parameters, and the description adds substantial meaning beyond it: product meanings and prices, the default SKU, token provenance, and single-use/amount-cap behavior. Quantity is not elaborated beyond what the schema's min/max provides, but the rest of the parameter semantics are well enriched.

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's function: paying for prepaid units with a Stripe Shared Payment Token. It specifically enumerates the purchasable products (article, question_pack, visibility_scan, competitor_scan) with prices and default behavior, making it easy to distinguish from sibling tools like generate_article or get_credit_usage.

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 gives explicit when-to-use and when-not-to-use guidance. It states 'Only call this with a real token from your platform's payment system', explicitly warns against inventing tokens or asking users for card credentials, and directs agents to relay the buy link from payment_required instead if their platform cannot mint SPTs.

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