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

With annotations already indicating readOnlyHint=false and destructiveHint=false, the description adds valuable behavioral context: the row is deactivated rather than deleted, and historical events remain available via recent_alerts. It discloses ownership enforcement without contradicting any 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, front-loaded with the primary action ('Cancel a subscription by id'), and every sentence adds value. No fluff or redundancy.

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 tool's low complexity (one parameter, no output schema) and the presence of annotations, the description covers all essential aspects: what it does, ownership constraints, and the deactivation behavior. The reference to recent_alerts also helps the agent understand downstream effects. This is complete for the tool's scope.

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 description for 'id' is complete (100% coverage): 'Subscription id (uuid) returned by subscribe.' The description itself repeats 'by id' but adds no new meaning beyond the schema. This aligns with the baseline score of 3 for 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 clearly states the tool's function: 'Cancel a subscription by id.' It uses a specific verb (cancel) and resource (subscription), and the title 'Unsubscribe from Alerts' reinforces this. It is distinct from siblings like 'subscribe' and 'list_subscriptions'.

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 usage context: ownership is enforced ('you can only cancel your own subscriptions') and it explains the effect on data (deactivated, not deleted). However, it does not explicitly name alternatives or state when not to use it, which keeps it just short of a 5.

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