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

The description adds substantial behavioral detail: 'The row is deactivated (not deleted) so its historical events stay available via recent_alerts.' This goes beyond the annotations (which already note non-destructive mutation) by specifying retention semantics and side effects.

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 sentences, front-loaded with the action, and every clause adds value: action, ownership, deactivation behavior, and an explicit pointer to recent_alerts. No fluff.

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 single-parameter tool with no output schema, the description covers the essential behavior, side effects, ownership constraint, and related tool. No significant gaps.

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 already fully describes the id parameter. The description adds the constraint that the id must belong to the caller's own subscription ('Ownership is enforced'), which is not in the schema.

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?

"Cancel a subscription by id" is a specific verb+resource statement. The title "Unsubscribe from Alerts" reinforces the action, and it clearly differs 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 states 'Ownership is enforced — you can only cancel your own subscriptions,' giving a clear condition for use. It also mentions recent_alerts as an alternative for viewing historical events, but it does not explicitly point to list_subscriptions for discovery.

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