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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses two critical behaviors: ownership is enforced, and the row is deactivated rather than deleted, preserving history in recent_alerts. This adds meaningful context not captured by the schema or annotations.

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 succinct sentences: the first states the action, the second explains the side effect. No wasted words, front-loaded with the verb and resource.

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?

The description explains the purpose, ownership constraint, and deactivation side effect. There's no output schema, but for a simple one-parameter cancellation tool, the description is sufficient. It could mention return values or confirmation, but that's minor given the tool's simplicity and comprehensive annotations.

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 coverage is 100%, so the parameter is well-described. The description adds value by explaining that the id is your own subscription (ownership enforcement), and that it's a subscription id returned by subscribe. This clarifies the semantic context beyond the schema's simple type.

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 uses the specific verb 'Cancel' and resource 'subscription by id', clearly distinguishing from sibling tools like subscribe, list_subscriptions, and recent_alerts. It states the core action unambiguously.

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 contextual guidance by stating ownership enforcement and the deactivation behavior, which tells the agent when it's appropriate to call (to cancel a subscription you own). However, it doesn't explicitly name alternative tools or describe when-not-to-use scenarios, though the context makes this inferred.

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