Pay: subscriptions cancel

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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=true), but the description adds genuinely non-obvious behavior: the cancellation is scheduled rather than immediate, the customer retains access and is not recharged, and the action is reversible via pay_subscriptions_resume. It also flags the user-confirmation requirement. It does not mention auth scopes or rate limits, which keeps it short of perfect.

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?

Front-loaded with the core action, then layered: timing semantics, reversibility, sibling alternatives, platform exception, and the destructive-action warning. Every sentence carries distinct information and none repeats the name or title.

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 one-parameter mutation with no output schema, everything an agent needs is present: what happens to the subscription, when, whether it can be undone, how to escalate to immediate termination, and when the tool doesn't apply (Apple). Nothing material is missing.

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 100% and the single `id` parameter is fully documented in the schema, including a pointer to pay_subscriptions_list for discovery. The description adds no parameter-level detail, so the baseline 3 for schema-covered parameters 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?

States a specific verb and resource ('Cancel a subscription') and immediately qualifies the semantics: the cancel is deferred to the end of the current billing period. It is clearly distinguishable from pay_subscriptions_force_expire and pay_subscriptions_delete, which are named in the description itself.

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?

Explicit routing: use pay_subscriptions_resume to reverse before period end, pay_subscriptions_force_expire to end access now, and Apple subscriptions must be cancelled by the customer in the App Store. Both the alternative and the condition that selects each one are given, plus an out-of-band exception case.

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