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

Annotations already declare destructiveHint=true and readOnlyHint=false, but the description adds material context beyond them: pending reminders are cancelled and never fire, and the result reports the cancelled-reminder count. The proposal handshake (status='confirmation_required', action_id, plan_token) is also disclosed, though the two confirmation passages partly repeat each other rather than adding distinct detail.

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 core behavior and side effects are front-loaded and easy to scan. The confirmation mechanics are stated twice — once inline and once in a dedicated CONFIRMATION block — which adds bulk without adding new information.

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 single-parameter destructive tool with no output schema, the definition covers the side effects, access boundary, required confirmation handshake, and the shape of the result. An agent has everything needed to invoke it and to know it must route through confirm_action.

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% for the single id parameter, which accepts integer or string, so the description must carry the burden. It clarifies that the id identifies one of the caller's own subscriptions, but does not specify the accepted id format or what happens if the id is unknown or belongs to someone else.

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 first sentence gives a specific verb, resource, and scope: delete a subscription by id and cancel its pending reminders. It also bounds reachability to the caller's own subscription, so an agent can distinguish it from update_subscription or get_subscription without inspecting schemas.

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 definition states the prerequisite flow explicitly: the caller confirms via confirm_action, and the write occurs only after confirm_action returns. It also states an exclusion (only the caller's own subscription is reachable), leaving little to inference about when this tool applies versus its siblings.

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