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

Beyond the annotations' destructiveHint=true, the description adds useful behavioral context: it discloses the concrete destruction ("remove the saved card") and the postcondition ("Purchases need a pay_url again"). It does not flag the non-idempotent behavior or any auth requirement, but the added effect/consequence detail is genuinely helpful.

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?

Two short sentences with the actor front-loaded and no filler; every clause carries meaning. Slightly telegraphic but structurally sound.

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 zero-parameter destructive mutation with no output schema, the description covers who, what, the destructive effect, and the consequence for future purchases. It omits auth requirements and reversibility, but annotations already carry the safety profile, so it is largely sufficient.

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 tool takes zero parameters and the schema is empty, so there are no parameter semantics to document. Per the rubric, a zero-parameter tool has a baseline of 4.

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 verb (end/revoke) and resource (card mandate), plus the concrete side effect of removing the saved card. It is clearly distinguishable from its inverse sibling set_mandate, though it never names that counterpart explicitly.

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?

Scopes the actor ("Buyer:") and gives the downstream consequence ("Purchases need a pay_url again"), which implies when this is relevant. However, it names no alternative (set_mandate, mandate_status) and gives no explicit when-not guidance, 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.