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

The annotations already declare this is a non-read-only, non-destructive, idempotent, closed-world operation. The description adds important behavior beyond those annotations: the action only marks the subscription in Dandori, has no external provider effect, and is reversible from the app.

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 a single front-loaded sentence with a compact parenthetical that carries the key caveat. Every clause adds useful information and there is no redundant wording.

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 simple three-parameter mutation with full schema coverage and informative annotations, the description supplies the essential behavioral caveats: local-only cancellation, no provider action, and reversibility. No output schema exists, so the description does not need to explain return values.

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%, so the schema already documents the id, reason, and cancellation_date parameters. The description does not add further meaning about parameter formats or defaults, so the baseline score of 3 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?

The description states a specific verb and resource: marking a subscription as cancelled in Dandori. The parenthetical explicitly distinguishes this local status change from cancelling with the provider, so an agent can identify the operation without opening the schema.

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?

It gives clear usage context by stating that the tool does not cancel anything with the provider and that the subscription can be reactivated from the app. It does not name an alternative tool for provider-side cancellation, but it establishes the boundary for when this local marking applies.

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