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

Annotations are absent, so the description carries full responsibility. 'Cancel a subscription' implies a mutation but does not disclose whether cancellation is reversible, what happens to the subscription's data, or side effects like billing or access changes. This is a significant transparency gap.

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 extremely terse ('Cancel a subscription.') but this is under-specification rather than effective conciseness. It omits essential details that could have been included in a slightly longer but still efficient description.

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 mutation tool with no annotations, output schema, or parameter details, the description is insufficient. It does not explain return values, error conditions, or behavioral consequences, making it incomplete for an agent to invoke safely and understand outcomes.

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 has one required parameter 'id' (string) with no description, and the tool description does not explain its meaning, format, or how it identifies the subscription. With 0% schema description coverage, the description fails to compensate.

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 a specific verb ('Cancel') and resource ('a subscription'), clearly distinguishing it from siblings like create_subscription, get_subscription, and list_subscriptions. It is unambiguous about the core action.

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?

No usage guidance is provided. The description does not state when to use this tool, any prerequisites, or alternative tools to consider, leaving the agent without context for choosing it over other subscription-related tools.

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