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

Goes meaningfully beyond annotations by disclosing the offloaded payment flow: "Payment happens only on Stripe's page; the tool takes no card details." That clarifies an openWorld, non-readonly side effect in a way the hints alone cannot. It does not mention that each invocation spawns a fresh non-idempotent checkout session or how long the link lives, which is the missing piece.

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 tight sentences with zero filler; the return value and plan scope are front-loaded, and the payment-safety caveat follows immediately after.

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 three-parameter, side-effecting, open-world tool with no output schema, it covers the essentials: what comes back (a Stripe link), what the token means, and that no card data is handled. It falls short only on the returned link's lifetime/reuse behavior and on the undocumented period parameter.

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 only 33%, so the description must carry weight; it does map "Pro or Business plan" onto the plan enum and ties "confirmed account" to setup_token. However, the period parameter (monthly/yearly) is never mentioned in either the description or the schema, leaving one of three parameters semantically bare.

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 and resource ("Returns a Stripe Checkout link") scoped to the Pro/Business plans on a confirmed account. That scope cleanly separates it from siblings like recommend_plan (pre-purchase advice) and check_account_status (verification), so an agent can pick it without opening the schema.

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?

Preconditions are stated explicitly — the account must be confirmed and the user must already have chosen a paid plan — plus the setup_token's origin (create_account) is named in the schema. There is no explicit exclusion or named alternative (e.g., what to do if the user has not yet picked a plan), so it stops short of a 5.

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