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

The description adds significant behavioral context beyond annotations: ownership enforcement, deactivation instead of deletion, and preservation of historical events. Annotations already indicate non-destructive (destructiveHint=false) and idempotent (idempotentHint=true), and the description aligns with and enriches these.

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 efficient sentences, front-loaded with the core action. Every sentence serves a purpose: first states what it does, second explains behavioral nuances. No wasted words.

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 fully covers purpose, ownership, outcome (deactivation), and side effects (historical events preserved). Annotations and schema are rich enough, and the description completes the picture.

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 sole parameter 'id' is fully described in the schema (100% coverage). The description adds the ownership constraint ('you can only cancel your own subscriptions'), which provides contextual meaning beyond the schema's type and description.

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 action ('Cancel a subscription by id'), identifies the resource ('subscription'), and distinguishes from sibling tools like 'subscribe' and 'list_subscriptions' through ownership enforcement and deactivation behavior.

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 context: ownership enforcement means only your own subscriptions can be canceled, and it mentions that the row is deactivated (not deleted) with historical events remaining accessible via recent_alerts. While alternatives aren't explicitly named, the implied usage is well-defined.

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