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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=true), the description discloses crucial behavioral details: the row is deactivated, not deleted, and historical events remain available via recent_alerts. It also explains ownership enforcement. This is valuable context not captured by annotations alone.

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 primary action, followed by the ownership constraint and side effect. Every sentence contributes essential information without redundancy or 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?

Given the simplicity of the tool (one parameter, no output schema), the description is complete: it states the action, ownership rules, and the deactivation behavior. The lack of return-value documentation is acceptable since no output schema exists and the annotation idempotentHint covers repeatability.

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 provides full coverage of the only parameter 'id' (description: 'Subscription id (uuid) returned by subscribe'). The tool description merely says 'by id', adding no new meaning beyond the schema. Baseline 3 is appropriate when schema does the heavy lifting.

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 'Cancel a subscription by id' with a specific verb and resource, clearly distinguishing it from sibling tools like subscribe (create) and list_subscriptions (read). It also adds the ownership enforcement note, further clarifying its scope.

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 gives clear usage context by mentioning ownership enforcement ('you can only cancel your own subscriptions'), implying the tool is for canceling your own subscriptions. However, it does not explicitly mention alternatives or exclusion cases, such as using list_subscriptions to find the id or using subscribe to create a subscription.

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