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

Annotations already indicate destructive and idempotent behavior, and the description adds useful context beyond them: it releases any order draft, has no effect on completed/canceled sessions, and requires both meta fields. There is no contradiction with the 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?

Three concise, purposeful sentences with no filler. The action is front-loaded, the edge-case behavior is stated, and the required metadata is called out. Every sentence earns its place.

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 destructive idempotent operation with an output schema, the description covers purpose, effect, no-op cases, and prerequisites. The only meaningful gap is the undocumented `id` parameter, which prevents a perfect score.

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?

Schema description coverage is 0%, so the description must compensate, but it only explains the meta requirements and never describes the required `id` parameter. The description adds no meaning for `id`, leaving the agent to infer that it is the checkout session identifier from the tool name and context.

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 a specific action ('Cancela una sesión de checkout UCP abierta') and its concrete effect ('libera cualquier borrador de pedido'). It also distinguishes itself from related checkout tools by focusing on cancellation and explicitly noting that completed or canceled sessions are unaffected.

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 makes the intended use clear: cancel an open UCP checkout session. It also provides an implicit exclusion ('Una sesión completada o cancelada no cambia') and states required prerequisites. It does not explicitly name alternatives like complete_checkout, but the context is otherwise strong.

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