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

The description adds meaningful behavioral context beyond the annotations: it states the action is not a delete but a deactivation, explains that historical events remain available via recent_alerts, and enforces ownership. These details complement the idempotent and non-destructive hints, providing a clear picture of side effects and permissions.

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 three sentences, each serving a distinct purpose: action, ownership constraint, and deactivation behavior. It is tightly written with no unnecessary information or repetition.

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 single-parameter tool with no output schema, the description is quite complete: it covers the action, the ownership constraint, and the post-effect on historical events. It does not explicitly describe error handling for invalid ids or unauthorized attempts, but given the annotations on idempotency and non-destructiveness, it is sufficient for confident invocation.

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 input schema already documents the single 'id' parameter with 100% coverage, noting it is the subscription id returned by subscribe. The description merely says 'by id' without adding new parameter-specific details, so the baseline 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 clearly states the action ('Cancel a subscription by id') and the resource (subscription). It distinguishes from siblings by explaining that the row is deactivated, not deleted, and that ownership is enforced, providing a precise and unambiguous purpose.

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 implies when to use the tool (to cancel a subscription) and mentions the ownership restriction, which serves as an implicit exclusion. However, it does not explicitly mention alternatives (e.g., list_subscriptions) or explicitly state when not to use it, so the guidance is only partially developed.

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