Pay: plans create

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

Annotations declare this is a non-read-only, non-destructive, non-open-world write, so safety is partly covered. The description adds real value beyond that: interactive prompting for missing fields, the defaults applied (gbp, monthly, type web, active), the downstream Stripe product/price sync gated on Connect onboarding, and the reassurance that nobody is charged until a user subscribes.

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, front-loaded with the core action and the interactive behavior. The second sentence is a long multi-clause run-on packing defaults, Stripe sync, billing reassurance and Apple mapping, but every clause carries information.

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 16-param, zero-required, no-output-schema tool, the description covers the key agent questions: defaults, interactive prompting, the Stripe side effect, and billing safety. It could say a bit more about what is returned or about the all-optional parameter set, but it is largely sufficient with annotations covering the write profile.

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 and the schema already documents every field including its create-defaults. The description only reinforces the same defaults and briefly explains apple_product_id's mapping purpose, adding little beyond the schema text.

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?

States a specific verb+resource ('Create a subscription plan') and even parenthesizes what a plan is ('a recurring price end users can buy'), so the agent knows the domain object. It does not explicitly contrast with sibling pay_plans_update or pay_plans_list, but the create verb makes the distinction obvious.

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?

Usage is implied by 'create' and the note about setting the Apple product id to map an in-app purchase hints at a specific use case. However, there is no explicit when-to-use/when-not guidance or reference to the alternative tools (pay_plans_update, pay_plans_list) for evolving or inspecting existing plans.

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