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

The description discloses important behavior beyond the annotations: every call creates a new unpaid order, retrying is unsafe, the token is a secret, and email delivery is a side effect. It also explains topup semantics and the embargo error. These details meaningfully inform an agent about side effects and non-idempotency, which annotations only partially signal.

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 dense but every sentence adds value: purpose, return values, retry warning, parameter clarifications, error meaning, and alternative tool. The most critical constraints are front-loaded, and there is no filler or repetition of schema details.

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 mutation tool with six parameters and complex side effects, the description covers the key operational facts: what is returned, how to use optional parameters, non-idempotency, secret handling, and an alternative path. An output schema exists, so detailed return structure does not need to be duplicated here.

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?

With 0% schema description coverage, the description carries the burden of explaining parameters. It explains period_num (1–365, daily_unlimited only), topup_iccid (with plan_id from list_topups), email (optional eSIM delivery), and lang (order page language). It does not fully clarify payment_method semantics beyond the enum, and lang is only implied, so it is not a perfect 5.

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 opens with a specific verb and resource: 'Create an order for a person to pay.' It explains the distinct artifacts returned (checkout_url, order_url, token) and differentiates itself from purchase_esim, which is the wallet-payment alternative. This clearly distinguishes the tool from its siblings.

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 explicit usage guidance: confirm the plan and price first, do not retry while a checkout is open, and use purchase_esim for wallet payments. It also flags a 403 as an embargoed jurisdiction, giving the agent actionable context for handling errors and choosing alternatives.

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