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

Even though annotations already mark the operation as non-read-only and not idempotent, the text adds crucial behavior: the tool has side effects (creates a checkout), requires relaying returned notes verbatim, must be followed by order-status verification, and has rate limits. It also warns against assuming fulfillment based on the user's claim of payment.

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 text is long but organized into labeled mandatory sections and front-loads the most critical rule at the top. There is slight repetition of schema-provided enum mapping, but the operational details justify the length.

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?

The description covers prerequisites, exact conversational prompts, parameter semantics, post-call verification, output fields to relay, and rate limits. Since there is no output schema, the mention of payment_url, session_id, and the three notes provides the necessary contract for the caller.

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?

Although schema coverage is 100%, the description meaningfully extends the schema: it clarifies customer_country means billing/residence country, not destination, and instructs the agent to ask rather than guess. For activation_mode, it provides the customer-safe labels and the exact natural-language question, which is far more actionable than the raw enum alone.

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 opening sentence, 'Create a Stripe checkout link for an eSIM package', names a specific verb, object, and resource, which is enough to separate this from the sibling tools. It is not a tautology and clearly identifies the tool's 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?

The description gives a mandatory pre-step (ask for customer_country), detailed rules for choosing activation_mode including the worldwide-plan exception, exact user-facing language, and a mandatory post-step to call check_order_status. It explicitly tells the agent what to ask, when to wait, and not to assume payment means the eSIM is ready.

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