Create Subscription

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

Annotations already indicate destructiveHint=true. Description adds no additional behavioral context beyond the creation action, such as triggers, side effects, or confirmation requirements. No contradictions with 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?

Single sentence, direct and front-loaded with verb and resource. No unnecessary words. Every word earns its place.

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?

With 11 parameters, nested items, and no output schema, the description is insufficient. It does not explain typical workflow, prerequisites (e.g., customer must exist), or what happens upon creation (e.g., invoice generation, payment attempt). A more comprehensive description is needed for such a complex 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?

Input schema covers all 11 parameters with descriptions (100% coverage). The description adds no parameter-specific information beyond what schema provides, so 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?

Clearly states 'Create a new subscription for a customer' with a specific verb and resource. Requirement for at least one price item adds clarity. Distinguishes from siblings like cancel_subscription and update_subscription.

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?

Describes a precondition (requires at least one price item) but does not provide guidance on when to use this tool versus alternatives like create_checkout_session or create_invoice. No explicit when-to-use or when-not-to-use.

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