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

Annotations indicate readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description adds 'The row is deactivated (not deleted) so its historical events stay available via recent_alerts,' which discloses the non-destructive behavior and links to a sibling tool, providing valuable context beyond 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 core purpose and ownership constraint, then immediately addressing behavioral side effects. Every sentence adds value with no 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 required parameter, no output schema), the description covers purpose, ownership enforcement, and the deactivation effect completely. No gaps are present for an agent to use the tool correctly.

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 description coverage is 100%, with the 'id' parameter described as 'Subscription id (uuid) returned by subscribe.' The description adds 'by id' but does not significantly enhance understanding beyond the schema. Per guidelines, baseline 3 is appropriate.

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 'Cancel a subscription by id,' which is a specific verb+resource combination. It clearly distinguishes from sibling tools like 'subscribe', 'list_subscriptions', and 'recent_alerts' by describing the cancel action and unique ownership enforcement.

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 states 'Ownership is enforced — you can only cancel your own subscriptions,' providing clear context on when to use this tool (for your own subscriptions) and an implicit exclusion (cannot cancel others'). However, it does not explicitly mention alternatives or when not to use, but the guidance is sufficient.

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