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

Beyond annotations (which indicate idempotent and non-destructive behavior), the description explicitly states that the row is deactivated and not deleted, preserving historical events via recent_alerts. This adds meaningful behavioral context about the operation's side effects and data retention.

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 short sentences each add distinct information: the action, ownership restriction, and the deactivation side effect. It is front-loaded and free of redundancy, making it highly readable and efficient.

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?

Given the single parameter, no output schema, and sibling tools, the description covers the essential context: what happens to the subscription, who can perform it, and where historical data remains available. It is sufficiently complete for a simple mutation tool.

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 schema fully documents the single parameter (id) with the same 'returned by subscribe' phrasing. The description adds nothing new about the parameter semantics beyond restating that it is a subscription id, so the baseline score of 3 applies.

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 starts with the specific verb 'Cancel' and resource 'subscription', clearly stating the action. It distinguishes from sibling tools like subscribe, list_subscriptions, and recent_alerts by focusing on the cancellation action and its side effects.

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 provides clear context about ownership enforcement and the deactivation behavior, which helps decide when to use this tool. It doesn't explicitly name alternatives but the context is sufficient for a straightforward unsubscribe action.

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