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

Beyond annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false), the description adds valuable behavioral context: the row is deactivated not deleted, and historical events remain accessible via recent_alerts. This enhances the agent's understanding without contradicting 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?

The description is two sentences, front-loaded with the primary purpose, and contains no redundant or unnecessary words. Every sentence adds value.

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 tool's simplicity (single parameter, no output schema, annotations present), the description adequately covers purpose, ownership, and side effects. It references the related tool 'recent_alerts'. Lacks mention of error conditions or prerequisites, but overall complete enough.

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% and the description does not add any additional parameter semantics beyond what the input schema already provides. The schema describes the 'id' parameter clearly as 'Subscription id (uuid) returned by subscribe.' No extra clarification needed.

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') and the resource ('subscription'). The verb 'cancel' and resource 'subscription' are specific and distinct from sibling tools like 'subscribe' (create) and 'list_subscriptions' (list).

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 by stating ownership enforcement ('you can only cancel your own subscriptions') and the deactivation behavior. It does not explicitly list when not to use or name alternatives, but the context is sufficient for an agent to understand when to invoke this tool.

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