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

The description adds significant context beyond annotations: it explains the row is deactivated rather than deleted, and historical events remain accessible via recent_alerts. This complements the annotations (destructiveHint=false, idempotentHint=true) without contradiction.

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 with no redundant information. The action is front-loaded, and every sentence adds value: first states the action and ownership, second clarifies the behavioral outcome.

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 mutation tool with one parameter and full annotations, the description covers purpose, behavior, ownership constraints, and side effects. No output schema is needed, and historical linkage is provided.

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 has 100% coverage for the single parameter 'id', including a clear description. The tool description does not add additional parameter semantics, meeting the baseline 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 verb 'Cancel a subscription' and identifies the resource by id. It distinguishes from siblings like 'subscribe' and 'recent_alerts' by explaining the outcome (deactivation vs deletion) and linking to historical availability.

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 explicitly mentions ownership enforcement ('you can only cancel your own subscriptions'), providing clear context for when to use the tool. It implies not to use for others' subscriptions but does not enumerate alternatives beyond the mention of recent_alerts.

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