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

Annotations only carry generic hints, so the description carries the behavioral burden. It reveals this is a state-changing operation, explains amount floors and caps, discloses deposit expiration (~15 minutes), includes network fees, and tells the agent to poll until paid. No contradiction with annotations.

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 core purpose, constraints, and payment instructions are front-loaded and organized well. However, the 'every purchase returns 3% cashback' clause is tangential to invoking create_deposit and adds noise, so not every sentence fully earns its place.

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 thoroughly covers the crypto payment flow, card flow, amount constraints, expiry, and the follow-up polling via get_deposit. The main gap is that 'needs the wallet code' is not tied to any schema parameter or explained in terms of where the agent supplies it, and the source of the polling token is only implicit.

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 0%, but the description compensates richly: it defines the amount_usd limits, gives the allowed crypto currency list for payment_method 'crypto', and explains how the response carries `pay` details. The only parameter not described, lang, is self-explanatory via its title and default.

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 states a clear verb and resource: it opens a wallet top-up and returns what is needed to pay it. It also distinguishes itself from siblings by explaining the crypto `pay` flow versus the card `checkout_url` flow, so an agent can tell it apart from tools like get_deposit and create_checkout.

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 concrete when-to-use guidance: when payment_method is crypto, pass a specific currency; when it is card, only checkout_url is returned; and after creating the deposit, poll get_deposit(token). It does not explicitly frame when not to use this tool versus alternatives, but the crypto/card distinction provides clear usage context.

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