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

The description goes beyond the annotations by clarifying that the row is deactivated, not deleted, which explains the destructiveHint=false annotation and prevents a dangerous misunderstanding. It also discloses ownership enforcement and the preservation of historical events, offering valuable behavioral context not present in the structured metadata.

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 core action, and every clause adds important detail. It is concise, structured effectively, and free of redundant information.

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 mutation tool with a single parameter and no output schema, the description covers the essential aspects: the action, the target, ownership constraints, the side effect (deactivation), and the relationship to recent_alerts. No critical information is missing for an agent to use it correctly.

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 input schema already provides a clear description for the 'id' parameter, but the description adds meaningful context by stating that ownership is enforced, implying the id must be a subscription owned by the caller. This clarifies how to use the parameter beyond its schema definition and compensates for the minimal schema detail.

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 verb ('Cancel') and resource ('a subscription by id'), making the tool's function immediately obvious. It also differentiates from sibling tools like subscribe and list_subscriptions by specifying cancellation semantics.

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, a key prerequisite, and points to recent_alerts for accessing historical events, providing useful context. However, it does not explicitly name alternatives or exclusion criteria (e.g., 'use subscribe to create'), so it stops short of a fully explicit when/when-not guide.

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