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

Annotations are all false and thus provide little signal, so the description carries the burden. It discloses meaningful behaviors: buyer account creation/linking with an email access link, charging conditions for nota-simple, browser completion for subscriptions, and the required ucp-agent meta. It does not explicitly clarify charge timing for informe items or create-vs-complete side effects, which is a moderate gap.

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 clause earns its place: purpose, version/date, product catalog, pricing, constraints, buyer behavior, return value, and authentication requirement. It is front-loaded with the core action and avoids fluff.

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?

The description covers the essentials needed to call create_checkout: product identifiers, required meta, buyer behavior, and return shape. Given the existing output schema and sibling tools, it is mostly complete, but it does not mention the checkout completion/cancellation flow or payment instrument usage, which would help an agent navigate the full workflow.

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 schema description coverage at 0%, the description compensates strongly: it enumerates exact item.id formats with prices, specifies one product/quantity 1, explains buyer.email account behavior, and requires meta['ucp-agent'] with a profile URL. This adds substantial meaning beyond the raw JSON Schema.

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?

States a specific action ('Crea una sesión de checkout UCP') and a concrete resource scope: buying informes, nota simple, or a Subastech subscription. The product list and prices make the purpose unmistakable and differentiate it from sibling checkout tools like complete_checkout, cancel_checkout, and get_checkout.

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?

Provides clear context for when to invoke it: creating a checkout for one of the enumerated products. It also states constraints (one product per session, quantity 1, buyer email required). However, it never names or contrasts with sibling tools such as complete_checkout or cancel_checkout, so the when-not-to-use guidance is left implicit.

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