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

The description adds significant behavioral detail beyond the annotations: it discloses ownership enforcement ('you can only cancel your own subscriptions'), explains that the row is deactivated rather than deleted, and clarifies that historical events stay accessible. This aligns with and enriches the destructiveHint=false and idempotentHint=true annotations.

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 two sentences that front-load the core action ('Cancel a subscription by id') and then add essential caveats about ownership and deactivation. There is no filler; every sentence contributes meaningful 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 simple one-parameter tool with no output schema, the description covers the action, ownership constraint, and the persistence of historical data via recent_alerts. It stops short of describing specific error responses when ownership fails, but the tool's simplicity and the clarity of the effect make this a minor gap.

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 coverage is 100% and the parameter 'id' is already well-described as 'Subscription id (uuid) returned by subscribe.' The description repeats 'by id' without adding further semantics, so it does not exceed the baseline expected given the high schema coverage.

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 uses the specific verb 'Cancel' and identifies the resource 'a subscription by id,' clearly distinguishing it from sibling tools like 'subscribe' and 'list_subscriptions.' It is a specific and unambiguous statement of what the tool does.

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 contrasts with 'subscribe' by context. It also notes that historical events remain available via recent_alerts, providing useful post-condition context. It does not explicitly state when not to use it, but the intended use case is clear.

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