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

The description adds traits beyond annotations: ownership enforcement, row deactivation (not deletion), and availability of historical events via recent_alerts. Annotations already indicate non-destructive and non-read-only nature, but this adds context.

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?

Two concise sentences with front-loaded action. Every sentence adds value without wordiness.

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 tool with one parameter, strong annotations, and no output schema, the description sufficiently covers purpose, constraints, and side effects.

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?

With 100% schema coverage, the schema already fully describes the 'id' parameter as a UUID from subscribe. The description adds no further parameter meaning beyond 'by id', which is redundant.

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 'Cancel a subscription by id', specifying the verb and resource. It differentiates from siblings like subscribe and list_subscriptions by indicating it's for cancellation.

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 mentions ownership enforcement, implying only self-owned subscriptions can be cancelled, and indirectly references recent_alerts for historical events. However, it lacks explicit when-not-to-use guidance or direct alternatives.

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