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

The description goes beyond annotations by explaining ownership enforcement, that the row is deactivated not deleted, and that historical events remain available via recent_alerts. This aligns with destructiveHint=false and idempotentHint=true without contradicting them.

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?

Three concise sentences, each adding essential information: the action, the ownership constraint, and the deactivation behavior. No filler or 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?

For a simple single-parameter cancellation tool, the description covers the action, prerequisites (ownership), side effects, and how to access historical data afterward. The lack of output schema is not a gap here.

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 covers the single parameter fully (id returned by subscribe). The description adds meaning by specifying that the id is a subscription id and that ownership is enforced, reinforcing which id to provide.

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 states a specific verb and resource: "Cancel a subscription by id." It clearly differentiates from siblings like subscribe and list_subscriptions, and the deactivation detail adds further clarity.

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?

It provides clear context on ownership (only your own subscriptions) and the consequence (deactivation, history preserved). It doesn't explicitly state when not to use it, but the context strongly implies usage for stopping alerts while retaining history.

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