Update Subscription

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

No annotations are provided, so the description carries the full burden. It fails to disclose behavioral traits such as idempotency (though an idempotency_key parameter exists), potential side effects like proration or invoicing, permission requirements, or state constraints (e.g., cannot update canceled subscriptions). The list of changeable aspects is helpful but insufficient.

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 a single sentence that is concise and front-loaded with the action and changeable aspects. It could be more structured (e.g., listing parameters in a bullet format) but is efficient overall.

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 complexity (9 parameters, nested objects, no output schema), the description is incomplete. It does not explain return values, behavioral outcomes of different parameter combinations (e.g., proration_behavior, trial_end), or the overall effect of an update, which is necessary for an AI agent to use it correctly.

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 description coverage is 100%, so the baseline is 3. The description adds a high-level summary of changeable categories (items, payment method, etc.) but does not elaborate on parameter semantics beyond what the schema already provides, and it omits parameters like proration_behavior, coupon, and idempotency_key.

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 verb 'Update' and resource 'subscription', and lists the types of changes (items, payment method, trial, cancellation behavior, metadata), distinguishing it from related tools like create_subscription or cancel_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?

The description provides no guidance on when to use this tool versus alternatives (e.g., create_subscription, cancel_subscription), nor does it specify preconditions or exclusions. The context of modifying an existing subscription is implied but not explicitly stated.

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