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

Annotations show readOnlyHint=false, destructiveHint=false, idempotentHint=true. The description adds: 'Ownership is enforced', 'The row is deactivated (not deleted)', and 'historical events stay available via recent_alerts.' This provides useful behavioral context beyond annotations, with no contradiction.

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 sentences, zero waste. The first sentence states the action and key constraint, the second clarifies the behavioral effect. Every sentence serves a purpose.

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 tool has a single parameter, no output schema, and annotations are present. The description covers purpose, constraints, and result behavior. It lacks details on error cases (e.g., invalid id) but is otherwise complete for a simple mutation tool.

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%, with the 'id' parameter described as 'Subscription id (uuid) returned by subscribe.' The description mentions 'by id' but adds no additional meaning beyond what the schema already provides. Baseline score of 3 is appropriate.

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 'Cancel a subscription by id.' The verb 'cancel' and resource 'subscription' are specific. It distinguishes from sibling tools like 'subscribe' and 'list_subscriptions' by indicating this is the reversal action. Ownership enforcement is mentioned, adding 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?

The description provides a clear constraint: 'Ownership is enforced — you can only cancel your own subscriptions.' This implies when not to use it (to cancel others'). However, it does not explicitly mention alternatives or situations where this tool is inappropriate, but the context is strong enough for an agent to infer.

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